Direct fabrication of aligners for arch expansion

ABSTRACT

Systems, methods, and devices for producing appliances for expansion of the arch of a patient are provided. An arch expanding appliance comprises a force generating portion to apply an arch expansion force and a retention portion to hold the force generating portion on the teeth. The retention portion comprises a flexible portion and a stiff portion. The force generating portion applies a force to move teeth associated with the flexible portion, while the stiff portion resists movement of its associated teeth. The orthodontic appliances can be designed according to the specifications provided herein and manufactured using direct fabrication methods.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.62/189,271, filed Jul. 7, 2015, and U.S. Provisional Application No.62/189,301, filed Jul. 7, 2015, the disclosures of each of which areincorporated herein by reference in their entirety.

The subject matter of the following co-pending patent applications isrelated to the present application: U.S. application Ser. No.15/202,342, filed Jul. 5, 2016, entitled “MULTI-MATERIAL ALIGNERS”,which claims the benefit of U.S. Provisional Application No. 62/189,259,filed Jul. 7, 2015 and U.S. Provisional Application No. 62/189,282,filed Jul. 7, 2015; U.S. application Ser. No. 15/202,472, filed Jul. 5,2016, entitled “DIRECT FABRICATION OF ALIGNERS WITH INTERPROXIMAL FORCECOUPLING”, which claims the benefit of U.S. Provisional Application No.62/189,263, filed Jul. 7, 2015; U.S. application Ser. No. 15/202,348,filed Jul. 5, 2016, entitled “DIRECT FABRICATION OF ATTACHMENT TEMPLATESWITH ADHESIVE”, which claims the benefit of U.S. Provisional ApplicationNo. 62/189,259, filed Jul. 7, 2015, and U.S. Provisional Application No.62/189,282, filed Jul. 7, 2015; U.S. application Ser. No. 15/202,467,filed Jul. 5, 2016, entitled “DIRECT FABRICATION CROSS-LINKING FORPALATE EXPANSION AND OTHER APPLICATIONS”, which claims the benefit ofU.S. Provisional Application No. 62/189,301, filed Jul. 7, 2015, andU.S. Provisional Application No. 62/189,271, filed Jul. 7, 2015; U.S.application Ser. No. 15/202,254, filed Jul. 5, 2016, entitled “SYSTEMS,APPARATUSES AND METHODS FOR DENTAL APPLIANCES WITH INTEGRALLY FORMEDFEATURES”, which claims the benefit of U.S. Provisional Application No.62/189,291, filed Jul. 7, 2015, U.S. Provisional Application No.62/189,312, filed Jul. 7, 2015, and U.S. Provisional Application No.62/189,317, filed Jul. 7, 2015; U.S. application Ser. No. 15/202,299,filed Jul. 5, 2016, entitled “DIRECT FABRICATION OF POWER ARMS”, whichclaims the benefit of U.S. Provisional Application No. 62/189,291, filedJul. 7, 2015, U.S. Provisional Application No. 62/189,312, filed Jul. 7,2015, and U.S. Provisional Application No. 62/189,317, filed Jul. 7,2015; U.S. application Ser. No. 15/202,187, filed Jul. 5, 2016, entitled“DIRECT FABRICATION OF ORTHODONTIC APPLIANCES WITH VARIABLE PROPERTIES”,which claims the benefit of U.S. Provisional Application No. 62/189,291,filed Jul. 7, 2015, U.S. Provisional Application No. 62/189,312, filedJul. 7, 2015, and U.S. Provisional Application No. 62/189,317, filedJul. 7, 2015; U.S. application Ser. No. 15/202,139, filed Jul. 5, 2016,entitled “SYSTEMS, APPARATUSES AND METHODS FOR SUBSTANCE DELIVERY FROMDENTAL APPLIANCE”, which claims the benefit of U.S. ProvisionalApplication No. 62/189,303, filed Jul. 7, 2015; U.S. application Ser.No. 15/201,985, filed Jul. 5, 2016, entitled “DENTAL MATERIALS USINGTHERMOSET POLYMERS”, which claims the benefit of U.S. ProvisionalApplication No. 62/189,380, filed Jul. 7, 2015; and U.S. applicationSer. No. 15/202,083, filed Jul. 5, 2016, entitled “DENTAL APPLIANCEHAVING ORNAMENTAL DESIGN”, which claims the benefit of U.S. ProvisionalApplication No. 62/189,318, filed Jul. 7, 2015, the entire disclosuresof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Prior methods and apparatus of expanding a patient's palate can be lessthan ideal in at least some instances. Prior palate expanders can besomewhat uncomfortable to wear. Work in relation to embodiments suggeststhat the fit of prior palate expanders to the patient can be less thanideal, and that this less than ideal fit can result in discomfort anddecreased compliance with treatment. Also, prior methods and apparatusfor fabricating palate expanders can be somewhat more time consuming andcost more than would be ideal, such that fewer people can benefit fromthe use of palate expanders. Furthermore, prior palate expanders requireinconvenient adjustment on a daily or weekly basis by patients.

Additionally, some patients may have teeth arranged in a less than idealmanner, such that expansion of the arch with movement of the teeth canbe helpful. Prior methods and apparatus for expanding a patient's archcan be less than ideal in at least some respects. Work in relation toembodiments suggests that the fit of prior arch expanders to the patientcan be less than ideal, and that this less than ideal fit can result indiscomfort and decreased compliance with treatment. Also, prior methodsand apparatus for fabricating arch expanders can be somewhat more timeconsuming and cost more than would be ideal, such that fewer people canbenefit from the use of arch expanders.

In light of the above there is a need for an improved, patient specificpalate expanders and arch expanders having a better fit with the mouthof the patient, and designed to meet the patient's specific needs, whichcan be readily manufactured.

SUMMARY

In a first aspect, the methods and apparatus disclosed herein provideimproved palate expanders having improved fit with the mouth of thepatient. In many embodiments, the palate expander is customized to thedentitia and palate of the patient. The oral cavity of the patient canbe scanned to determine the size and shape of at least the teeth of theupper arch and palate. The scans can provide three dimensional profiledata of the upper teeth and palate, and this data can be used todetermine the shape profile of the palate expander. The palate expandercan be direct manufactured in accordance with the shape profile. Thepalate expander comprises a teeth-engaging portion and a forcegenerating portion such as a resilient structure or a force generatingportion. One or more extensions can extend between the teeth engagingportion and the force generating portion to couple the force generatingportion of the teeth engaging portion. The teeth engaging portion maycomprise a transparent shell having a plurality of tooth receivingcavities sized and shaped to receive a plurality of teeth of thepatient. The force generating portion is configured to provide outwardforces to the teeth to expand the palate. The force generating portionis sized and shaped to provide a gap between the palate and the forcegenerating portion when the teeth engagement portion has been placed onand engages the teeth. The teeth engagement portion, the forcegenerating portion and the extension portion can have three dimensionalshape profiles determined in response to the three dimensional profiledata of the mouth of the patient in order to customize the fit to themouth. The force generating structure can be configured to provide apredetermined amount of force to the teeth on opposing sides of theupper arch in response to the three dimensional shape profile data. Theforce generating structure can be sized and shaped and configured withdirectly fabricated material to provide a customized amount of force tothe mouth in response to the three dimensional profile data of themouth.

The palate expander can be directly fabricated in order to fit the upperarch and palate and provide improved strength, accuracy, which canresult in improved accuracy of the forces to the teeth, resulting inimproved performance and comfort. Also, the palate expander can beaccurately shaped to inhibit contact of the force generating portionwith the palate. The three dimensional shape profile of the palateexpander and can be determined in response to the three dimensionalprofile data. The direct manufacturing may comprise a continuouscrosslinking process in which the force generating portion and the teethengaging portion comprise crosslinked polymers and the force generatingportion and the teeth engaging portion are connected together withcross-linking. This cross linking of these structures provides furtherimproved accuracy of the forces to the teeth. The force generatingportion and the teeth engaging portions may comprise similar polymers.Alternatively the force generating portion and the teeth engagingportion may comprise different polymers.

The force generating portion can be configured in many ways. The forcegenerating portion may comprise resilient structure such as a springfabricated with direct manufacturing. The resilient structure can beconfigured in many ways and may comprise one or more of a coil, leafsprings, a chevron pattern, or bendable extensions. Alternatively or incombination, the force generating portion may comprise a hydratablepolymer that swells when placed in the mouth and hydrated. Thehydratable polymer may comprise a stiff polymer with sufficient rigidityto urge the teeth on opposing sides of the arch away from each other.The force generating portion may comprise a crosslinked polymer havingless crosslinking than the tooth engagement portion, for example. Theextensions, when included, may comprise more crosslinking than the forcegenerating portion, for example. In many embodiments, the teeth engagingportion, the force generating portion and the extension portion comprisesimilar polymer material. The similar polymer material may have lesseramounts of cross-linking to provide the force generating portion.Varying the cross-linking as the palate expander is formed can allow thesame prepolymer material to be used for the teeth engaging portions, theforce generating portion and the extension portion. Using similarprepolymer material and polymer material for the teeth engaging portion,the force generating portion and the extension portion may have theadvantage of increased strength and predictability. It is alsocontemplated, however, that different materials can be used to directlyfabricate the palate expander.

In many embodiments, an appliance to expand a palate of a patientcomprises a teeth engagement portion or component and a force generationportion or component. The teeth engaging component comprises a pluralityof teeth engagement structures. The force generating component comprisesa plurality of engagement structures to engage corresponding structuresof the teeth engagement component in order to increase a size of thepalate.

In many embodiments, an appliance to expand a palate of a patientcomprises a teeth engaging component and a sintered metal forcegenerating component. The teeth engaging component comprises a pluralityof teeth engagement structures. The sintered metal force generatingcomponent comprises a plurality of engagement structures to engagecorresponding structures of the teeth engagement component with force inorder to increase a size of the palate.

The materials and structures as disclosed herein can be combined in manyways. The appliance may comprise sintered material such as a sinteredmetal and a sintered plastic material, for example, and combinationsthereof.

The palate expander can be combined with orthodontic treatment. Thepalate expander may comprise a plurality of teeth receiving cavitiessized and shaped to move the received teeth along a treatment profile.The palate expander may comprise one of a plurality of palate expanderscomprising dental appliances having teeth receiving cavities sized andshaped to move teeth along an orthodontic treatment. The plurality ofpalate expanders can be applied in series and configured to expand thepalate along a palate treatment plan with the teeth as the teeth aremoved along a teeth treatment plan.

In a second aspect, the methods and apparatus disclosed herein provideimproved arch expanders having improved fit with the mouth of thepatient. In many embodiments, the arch expander is customized to thedentitia and arch of the patient. The oral cavity of the patient can bescanned to determine the size and shape of the teeth. The scans canprovide three dimensional profile data of the teeth, and this data canbe used to determine the shape profile of the arch expander. The archexpander can be direct manufactured in accordance with the shapeprofile. The arch expander may comprise a teeth retention portion tohold the appliance in place and a force generation portion to directteeth movement to a desired position. The teeth retention portion maycomprise a plurality of teeth engagement structures such as teethreceiving cavities or a plurality of extensions sized and shaped toextend at least partially around the teeth, for example around theteeth. The plurality of extension can extend into interproximal spacesof the teeth, and may comprise a soft material for patient comfort. Theteeth retention portion may comprise a soft material, such as an elasticmaterial. The force generating portion may comprise one or more of astiff material or an expandable material, for example. The forcegenerating portion may comprise a stiff material to engage the teeth andexpand the arch. Alternatively or in combination, the force generatingportion may comprise one or more of a compressible material, a resilientcompressible structure, or a hydratable material to apply force to theteeth. The rigid material can extend between the force generatingportion and the teeth to apply forces to the teeth expand the arch.

While the arch expander can be configured in many ways, the forcegenerating structure can be located between a mesial component and adistal component in order to urge the teeth apart in mesial opposingmesial and distal directions. The expander may comprise adjacent stiffsegments extending in mesial and distal directions, with the forcegenerating structure located therebetween.

The arch expander may comprise retention structures with a soft materialover the occlusal surface or no material over the occlusal surface toencourage tooth movement to a location suitable for engagement with anopposing tooth of an opposing arch.

The arch expander can be directly fabricated in order to fit the teethand provide improved strength, accuracy, which can result in improvedaccuracy of the forces to the teeth, resulting in improved performanceand comfort. The three dimensional shape profile of the arch expandercan be determined in response to the three dimensional profile data. Thedirect manufacturing may comprise a continuous crosslinking process inwhich the force generating portion and the teeth engaging portioncomprise crosslinked polymers and the force generating portion and theteeth engaging portion are connected together with cross-linking. Thiscross linking of these structures provides further improved accuracy ofthe forces to the teeth. The force generating portion and the teethengaging portions may comprise similar polymers. Alternatively the forcegenerating portion and the teeth engaging portion may comprise differentpolymers. The teeth engaging portion may comprise a rigid materialhaving structures sized and shaped to extend into the interproximalspaces of the teeth to improve engagement. Engagement of the teeth inthe interproximal spaces permits application of forces closer to thecenter of rotation of the tooth in order to decrease tipping of thetooth.

Although many of the components disclosed herein can be fabricatedtogether, in many embodiments components can be directly fabricatedseparately and provided with structures to allow coupling postfabrication. An appliance to expand an arch of a patient comprises ateeth engagement component and a force generating component. The teethengagement component comprises a plurality of teeth engagementstructures. The force generating component comprises a plurality ofengagement structures to engage corresponding structures of the teethengagement component to increase a size of the arch.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present disclosure will be obtained by reference tothe following detailed description that sets forth illustrativeembodiments, in which the principles of the invention are utilized, andthe accompanying drawings of which:

FIG. 1A illustrates a tooth repositioning appliance, in accordance withembodiments;

FIG. 1B illustrates a tooth repositioning system, in accordance withembodiments;

FIG. 1C illustrates a method of orthodontic treatment using a pluralityof appliances, in accordance with embodiments;

FIG. 2 illustrates a method for designing an orthodontic appliance, inaccordance with embodiments;

FIG. 3 illustrates a method for digitally planning an orthodontictreatment, in accordance with embodiments;

FIG. 4 is a simplified block diagram of a data processing system, inaccordance with embodiments;

FIG. 5 illustrates an orthodontic appliance comprising a palatalexpander portion within the mouth of a patient, in accordance withembodiments;

FIG. 6 illustrates a top view of an appliance comprising a palateexpander portion, a shell, and an extension structure joining the twotogether, in accordance with embodiments;

FIG. 7 illustrates an appliance which has been fabricated so as to avoidupwards pressure on a patient's palate, in accordance with embodiments;

FIG. 8A illustrates an appliance with palatal expander comprising afabricated spring structure, in accordance with embodiments;

FIG. 8B illustrates an appliance with palatal expander comprising afabricated echelon-patterned spring structure, in accordance withembodiments;

FIG. 8C illustrates an appliance with palatal expander comprising afabricated structure comprising compressible curved portions, inaccordance with embodiments;

FIG. 8D illustrates an appliance with palatal expander comprising afabricated jack structure comprising compressible hinged arms, inaccordance with embodiments;

FIG. 8E illustrates an appliance with palatal expander comprising amaterial that expands upon contact with human saliva, in accordance withembodiments;

FIG. 9A illustrates a removable palatal expander fabricated to mate withan orthodontic appliance, in accordance with embodiments;

FIG. 9B illustrates part of an aligner designed to mate with a palatalexpander, in accordance with embodiments;

FIG. 9C illustrates a prototype orthodontic appliance comprising both apalatal expander and an aligner in accordance with embodiments, inaccordance with embodiments;

FIG. 9D illustrates a 3D model of an appliance comprising a palatalexpander and an aligner in accordance with embodiments; and

FIG. 10 shows an orthodontic appliance comprising a plastic alignerportion and a metallic palatal expander in accordance with embodiments.

FIG. 11 illustrates a variety of different arch expander designs thatmay be incorporated into an orthodontic appliance in accordance withembodiments;

FIG. 12 illustrates a further embodiment in which an appliance may befabricated with an arch expander comprising a connective portion toapply forces between distant teeth in accordance with embodiments;

FIG. 13 illustrates an aligner design that may be used in conjunctionwith the connective portion illustrated in FIG. 12 to guide a toothmovement;

FIG. 14A illustrates an example of an appliance having an anterior tabarch element, according to embodiments;

FIG. 14B illustrates an example of an appliance having a rib feature,according to embodiments;

FIG. 15A illustrates an arch expander having a removable connectorcomponent fabricated to mate with an orthodontic appliance, inaccordance with embodiments;

FIG. 15B illustrates part of an aligner designed to mate with aremovable connector component, in accordance with embodiments;

FIG. 15C illustrates a prototype orthodontic appliance comprising both aremovable connector and an aligner, in accordance with embodiments;

FIG. 15D illustrates a 3D model of an appliance comprising a removableconnector component and an aligner, in accordance with embodiments; and

FIG. 16 shows an orthodontic appliance comprising a plastic alignerportion and a metallic connector component, in accordance withembodiments.

DETAILED DESCRIPTION

The entire disclosure of U.S. Application Ser. No. 62/052,893, filed onSep. 19, 2014, entitled “Arch Adjustment Appliance” is incorporatedherein by reference and suitable for combination in accordance withembodiments disclosed herein.

In many embodiments, a directly fabricated orthodontic appliance forexpanding a palate of a patient is provided. The appliance comprises ateeth engagement portion comprising a plurality of teeth engagementstructures and a force generating portion coupled to the teethengagement portion. The force generating portion comprises a hydratablepolymer configured to expand when contacting saliva of the patient.

In some embodiments, the force generating portion is shaped to apply apalate-expanding force to the lateral sides of the palate of the patientwhen worn. In some embodiments, the force generating portion isconfigured to apply a palate-expanding force to the teeth engagementportion when worn, thereby applying a palate expanding force to theteeth of the patient. In some embodiments, the force generating portionis shaped to provide a gap between the top of the force generatingportion and the palate when worn. In some cases, the teeth engagementportion and the force generating portion can comprise similar polymerswith different amounts of crosslinking, the force generating portioncomprising less crosslinking than the teeth engagement portion.

In many embodiments, a directly fabricated orthodontic appliance toexpand a palate of a patient is provided. The appliance comprises ateeth engagement portion comprising a plurality of teeth engagementstructures and a directly fabricated resilient structure coupled to theteeth engagement portion. In some cases, the resilient structurecomprises one or more of a spring, a leaf spring, a coil spring, or anelastic structure.

In many embodiments, a directly fabricated appliance is provided forexpanding a palate of a patient. The appliance comprises a teethengagement component comprising a plurality of teeth receivingstructures and a plurality of expander-engaging structures. Theappliance further comprises an expander component comprising a pluralityof engagement structures. The engagement structures of the expandercomponent engage corresponding expander-engaging structures of the teethengagement component. The engagement between the expander component andthe teeth engagement component applies a force to increase a size of thepalate when worn by the patient. In some cases, the respectiveengagement structures are reversibly couplable, such that the expanderportion is removable from the appliance. In some embodiments, theappliance comprises a sintered expander or a sintered teeth engagementcomponent. In some embodiments, the appliance comprises both a sinteredexpander and a sintered teeth engagement component, and each of theteeth engagement component and the expander component comprise arespective sintered material independently selected from sintered metal,sintered plastic, or a combination thereof.

In many embodiments, an appliance to expand a palate of a patient isprovided comprising a teeth engagement component comprising a pluralityof teeth receiving structures and an expander component coupled to theteeth engagement component. The expander component comprises ashape-memory material that changes from a first configuration to asecond configuration in response to a change in temperature. In somecases, the appliance is configured to apply a greater palate expandingforce in the first configuration than in the second configuration. Insome cases, the shape-memory material takes on the first configurationat about room temperature and takes on the second configuration at abouthuman body temperature.

In various embodiments, the appliances described herein can be shaped tobe manually removable by the patient. In some embodiments, the teethengagement portions of the appliances described herein can comprise aflattened occlusal surface for one or more molar-receiving structures.In various embodiments, the appliances described herein can be shaped toengage a temporary anchorage device in the palate of the patient toapply a palate expanding force when worn. In various embodiments, theappliances described herein can be configured to apply a tooth movingforce to one or more anterior teeth of the upper arch while expandingthe palate. In various embodiments, the appliances described herein canbe configured to provide a palatal expansion selected from the groupconsisting of a slow palatal expansion and a rapid palatal expansion.

In various embodiments, the force generating portion of the appliancesdescribed herein is configured to have a target palatal displacement,and to apply a palatal expansion force to expand the palate to thetarget palatal displacement. In some cases, the target palataldisplacement is adjustable.

In various embodiments, a plurality of the appliances described hereinare provided. The plurality of appliances are configured to expand thepalate when worn sequentially in accordance with a predetermined palateexpansion plan.

In many embodiments, a method of fabricating an orthodontic appliance isprovided. Scan data of an upper arch and a palate of a patient isreceived, and an amount of force to expand the palate is determined inresponse to the scan data. A shape profile of the appliance to engageteeth of the patient is determined and one or more of a force-generatingor a resilient structure is selected to provide the force. Directfabrication instructions are output to manufacture the appliance withthe teeth engaging structure and the force generating or resilientstructure.

In some cases, determining the shape profile includes determining ashape profile to inhibit contact with the top of the palate when worn.In some cases, the shape profile comprises an appliance shape to engagethe lateral sides of the palate of the patient, and the amount of forcecomprises a first amount of force applied directly to the palate and asecond amount of force applied to the teeth of the patient. In somecases, the force can comprise a force applied to a temporary anchoragedevice.

In some embodiments, the resilient structure comprises one or more of aspring, a leaf spring, a coil spring, or an elastic structure. In someembodiments, the force generating portion comprises one or more of asintered plastic or a sintered metal comprising a material and size andshape profile arranged to increase a size of the palate and the teethengaging portion comprises one or more of a sintered plastic or asintered metal comprising a material and size and shape profile arrangedto increase a size of the palate. In some embodiments, the methodfurther comprises outputting direct fabrication instructions tomanufacture a plurality of directly fabricated appliances configured toexpand the palate in accordance with a predetermined palate expansionplan. In some cases, the plurality of directly fabricated appliances arefurther configured to move the teeth in accordance with a predeterminedteeth movement treatment plan. In some cases, the plurality of directlyfabricated appliances comprises a plurality of appliances configured tobe placed on the teeth in series in accordance with a plurality ofstages of a treatment plan.

In some embodiments, determining an amount of force comprises selectinga rate of palatal expansion based and determining a force to produce theselected rate of palatal expansion.

In some embodiments, the method further comprises directly manufacturingthe appliance according to the direct fabrication instructions.

In some embodiments, the direct fabrication instructions includeinstructions to manufacture the appliance using an additivemanufacturing process. In some cases, the additive manufacturing processcomprises one or more of vat photopolymerization, material jetting,binder jetting, material extrusion, powder bed fusion, sheet lamination,or directed energy deposition. In some embodiments, the directfabrication instructions include instructions to manufacture theappliance using a subtractive manufacturing process.

In various embodiments, the scan data can include data of a temporaryanchorage device in the palate of the patient and the shape profilecomprises an engagement structure to engage the temporary anchoragedevice to apply a palate expanding force when the appliance is worn.

In many embodiments, an apparatus to expand an arch of a patient isprovided. The apparatus comprises a force generating portion to expandthe arch of the teeth, a flexible retention portion to hold the forcegenerating portion on the teeth, and a stiff retention portion coupledto the flexible retention portion. The stiff retention portion ispositioned adjacent to a first plurality of teeth receiving structuresof the flexible retention portion to receive a first plurality of teeth.The stiff retention portion resists movement of the first plurality ofteeth while allowing movement of a second plurality of teeth when theapparatus is worn.

In some embodiments, the force generating portion, the flexibleretention portion, and the stiff retention portion have been directlyfabricated together. In some embodiments, the force generating portioncomprises a stiff material. In some embodiments, the force generatingportion comprises one or more of a compressible material or a resilientcompressible structure to generate force to the teeth when placed. Insome embodiments, the stiff retention portion comprises one or more ribsor thickened portions. In some embodiments, the force generating portionspans the space between the bicuspid or molar teeth. In someembodiments, the apparatus comprises a plurality of materials.

In some embodiments, the force generating portion comprises one or moreof a compressible material, a hydratable material, or a resilientcompressible structure to generate force to the teeth when worn. In someembodiments, the flexible retention portion comprises a plurality ofteeth receiving structures, the plurality of teeth receiving structurescomprising one or more of a plurality of teeth receiving cavities or aplurality of teeth receiving extensions shaped to extend at leastpartially around received teeth.

In some embodiments, the force generating portion comprises adjacentstiff segments separated in a mesial-distal direction with an expansionforce generating portion extending therebetween. In some embodiments,the adjacent stiff segments comprise extensions sized to extend intointerproximal portions to engage the teeth, and soft retentionstructures are affixed to the stiff segments and sized and shaped toextend around the teeth and into interproximal portions to engage theteeth and retain one or more stiff segments against the teeth.

In various embodiments, the apparatus described herein comprise one ormore of a thermoplastic polymer, a thermoset polymer, a polymer ceramiccomposite, a carbon fiber composite, or a combination thereof.

In some embodiments, the apparatus is further configured to apply atooth moving force to one or more anterior teeth of the arch whileexpanding the arch.

In many embodiments, a method of fabricating an appliance to expand anarch of a patient is provided. Scan data of teeth of an arch of thepatient is received and a shape profile of the appliance to engage theteeth and expand the arch is determined. The appliance comprises a forcegenerating portion to expand the arch of the teeth, a flexible retentionportion to hold the force generating portion on the teeth, and a stiffretention portion coupled to the flexible retention portion. The stiffretention portion is positioned adjacent to a first plurality of teethreceiving structures of the flexible retention portion to receive afirst plurality of teeth, to resist movement of the first plurality ofteeth while allowing movement of a second plurality of teeth when theapparatus is worn. Direct fabrication instructions are output tomanufacture the appliance with a direct fabrication apparatus.

In some embodiments, the method further comprises determining an amountof force to expand the arch in response to the scan data and determininga shape of the force generating portion to provide the force to theteeth.

In some embodiments, the force generating portion is stiffer than theflexible retention portion. In some cases, the force generating portioncomprises adjacent stiff segments separated in a mesial-distal directionwith an expansion force generating portion extending therebetween. Insome cases, the appliance is configured to expand the arch withincreasing separation of the adjacent stiff segments in a mesial-distaldirection, and the adjacent stiff segments comprise extensions sized toextend into interproximal portions to engage the teeth. In some cases,the appliance further comprises soft retention structures affixed to thestiff segments and sized and shaped to extend around the teeth and intointerproximal portions to engage the teeth and retain one or more stiffsegments against the teeth.

In some embodiments, the method further comprises directly manufacturingthe appliance according to the direct fabrication instructions. In someembodiments, the direct fabrication instructions include instructions tomanufacture the appliance using an additive manufacturing process. Insome cases, the additive manufacturing process comprises one or more ofvat photopolymerization, material jetting, binder jetting, materialextrusion, powder bed fusion, sheet lamination, or directed energydeposition. In some embodiments, the direct fabrication instructionsinclude instructions to manufacture the appliance using a subtractivemanufacturing process.

In many embodiments, an appliance to expand an arch of a patient isprovided. The appliance comprises a teeth engagement componentcomprising a plurality of teeth engagement structures and a forcegenerating component coupled to the teeth engagement component. Theteeth engagement component comprises a plurality of structures disposedon the lingual side of the teeth engagement component, and the forcegenerating component comprises a plurality of engagement structures toengage the structures of the teeth engagement component to apply an archexpanding force.

In some embodiments, the force generating component is a sintered metalor sintered plastic force generating component comprising a plurality ofengagement structures to engage corresponding structures of the teethengagement component with force in order to increase a size of the arch.In some embodiments, the teeth engagement component is a sintered metalor sintered plastic teeth engagement component.

As used herein the terms “rigidity” and “stiffness” are usedinterchangeably, as are the corresponding terms “rigid” and “stiff.”

As used herein the term “and/or” is used as a functional word toindicate that two words or expressions are to be taken together orindividually. For example, A and/or B encompasses A alone, B alone, andA and B together.

As used herein a “plurality of teeth” encompasses two or more teeth.

In many embodiments, one or more posterior teeth comprises one or moreof a molar, a premolar or a canine, and one or more anterior teethcomprising one or more of a central incisor, a lateral incisor, acuspid, a first bicuspid or a second bicuspid.

The embodiments disclosed herein can be used to couple groups of one ormore teeth to each other. The groups of one or more teeth may comprise afirst group of one or more anterior teeth and a second group of one ormore posterior teeth. The first group of teeth can be coupled to thesecond group of teeth with the polymeric shell appliances as disclosedherein.

The embodiments disclosed herein are well suited for moving one or moreteeth of the first group of one or more teeth or moving one or more ofthe second group of one or more teeth, and combinations thereof.

The embodiments disclosed herein are well suited for combination withone or known commercially available tooth moving components such asattachments and polymeric shell appliances. In many embodiments, theappliance and one or more attachments are configured to move one or moreteeth along a tooth movement vector comprising six degrees of freedom,in which three degrees of freedom are rotational and three degrees offreedom are translation.

The present disclosure provides orthodontic systems and related methodsfor designing and providing improved or more effective tooth movingsystems for eliciting a desired tooth movement and/or repositioningteeth into a desired arrangement.

Although reference is made to an appliance comprising a polymeric shellappliance, the embodiments disclosed herein are well suited for use withmany appliances that receive teeth, for example appliances without oneor more of polymers or shells. The appliance can be fabricated with oneor more of many materials such as metal, glass, reinforced fibers,carbon fiber, composites, reinforced composites, aluminum, biologicalmaterials, and combinations thereof for example. In some cases, thereinforced composites can comprise a polymer matrix reinforced withceramic or metallic particles, for example. The appliance can be shapedin many ways, such as with thermoforming or direct fabrication asdescribed herein, for example. Alternatively or in combination, theappliance can be fabricated with machining such as an appliancefabricated from a block of material with computer numeric controlmachining.

Turning now to the drawings, in which like numbers designate likeelements in the various figures, FIG. 1A illustrates an exemplary toothrepositioning appliance or aligner 100 that can be worn by a patient inorder to achieve an incremental repositioning of individual teeth 102 inthe jaw. The appliance can include a shell (e.g., a continuous polymericshell or a segmented shell) having teeth-receiving cavities that receiveand resiliently reposition the teeth. An appliance or portion(s) thereofmay be indirectly fabricated using a physical model of teeth. Forexample, an appliance (e.g., polymeric appliance) can be formed using aphysical model of teeth and a sheet of suitable layers of polymericmaterial. In some embodiments, a physical appliance is directlyfabricated, e.g., using rapid prototyping fabrication techniques, from adigital model of an appliance. An appliance can fit over all teethpresent in an upper or lower jaw, or less than all of the teeth. Theappliance can be designed specifically to accommodate the teeth of thepatient (e.g., the topography of the tooth-receiving cavities matchesthe topography of the patient's teeth), and may be fabricated based onpositive or negative models of the patient's teeth generated byimpression, scanning, and the like. Alternatively, the appliance can bea generic appliance configured to receive the teeth, but not necessarilyshaped to match the topography of the patient's teeth. In some cases,only certain teeth received by an appliance will be repositioned by theappliance while other teeth can provide a base or anchor region forholding the appliance in place as it applies force against the tooth orteeth targeted for repositioning. In some cases, some, most, or even allof the teeth will be repositioned at some point during treatment. Teeththat are moved can also serve as a base or anchor for holding theappliance as it is worn by the patient. Typically, no wires or othermeans will be provided for holding an appliance in place over the teeth.In some cases, however, it may be desirable or necessary to provideindividual attachments or other anchoring elements 104 on teeth 102 withcorresponding receptacles or apertures 106 in the appliance 100 so thatthe appliance can apply a selected force on the tooth. Exemplaryappliances, including those utilized in the Invisalign® System, aredescribed in numerous patents and patent applications assigned to AlignTechnology, Inc. including, for example, in U.S. Pat. Nos. 6,450,807,and 5,975,893, as well as on the company's website, which is accessibleon the World Wide Web (see, e.g., the url “invisalign.com”). Examples oftooth-mounted attachments suitable for use with orthodontic appliancesare also described in patents and patent applications assigned to AlignTechnology, Inc., including, for example, U.S. Pat. Nos. 6,309,215 and6,830,450.

FIG. 1B illustrates a tooth repositioning system 110 including aplurality of appliances 112, 114, 116. Any of the appliances describedherein can be designed and/or provided as part of a set of a pluralityof appliances used in a tooth repositioning system. Each appliance maybe configured so a tooth-receiving cavity has a geometry correspondingto an intermediate or final tooth arrangement intended for theappliance. The patient's teeth can be progressively repositioned from aninitial tooth arrangement to a target tooth arrangement by placing aseries of incremental position adjustment appliances over the patient'steeth. For example, the tooth repositioning system 110 can include afirst appliance 112 corresponding to an initial tooth arrangement, oneor more intermediate appliances 114 corresponding to one or moreintermediate arrangements, and a final appliance 116 corresponding to atarget arrangement. A target tooth arrangement can be a planned finaltooth arrangement selected for the patient's teeth at the end of allplanned orthodontic treatment. Alternatively, a target arrangement canbe one of some intermediate arrangements for the patient's teeth duringthe course of orthodontic treatment, which may include various differenttreatment scenarios, including, but not limited to, instances wheresurgery is recommended, where interproximal reduction (IPR) isappropriate, where a progress check is scheduled, where anchor placementis best, where palatal expansion is desirable, where restorativedentistry is involved (e.g., inlays, onlays, crowns, bridges, implants,veneers, and the like), etc. As such, it is understood that a targettooth arrangement can be any planned resulting arrangement for thepatient's teeth that follows one or more incremental repositioningstages. Likewise, an initial tooth arrangement can be any initialarrangement for the patient's teeth that is followed by one or moreincremental repositioning stages.

FIG. 1C illustrates a method 150 of orthodontic treatment using aplurality of appliances, in accordance with embodiments. The method 150can be practiced using any of the appliances or appliance sets describedherein. In step 160, a first orthodontic appliance is applied to apatient's teeth in order to reposition the teeth from a first tootharrangement to a second tooth arrangement. In step 170, a secondorthodontic appliance is applied to the patient's teeth in order toreposition the teeth from the second tooth arrangement to a third tootharrangement. The method 150 can be repeated as necessary using anysuitable number and combination of sequential appliances in order toincrementally reposition the patient's teeth from an initial arrangementto a target arrangement. The appliances can be generated all at the samestage or in sets or batches (e.g., at the beginning of a stage of thetreatment), or the appliances can be fabricated one at a time, and thepatient can wear each appliance until the pressure of each appliance onthe teeth can no longer be felt or until the maximum amount of expressedtooth movement for that given stage has been achieved. A plurality ofdifferent appliances (e.g., a set) can be designed and even fabricatedprior to the patient wearing any appliance of the plurality. Afterwearing an appliance for an appropriate period of time, the patient canreplace the current appliance with the next appliance in the seriesuntil no more appliances remain. The appliances are generally notaffixed to the teeth and the patient may place and replace theappliances at any time during the procedure (e.g., patient-removableappliances). The final appliance or several appliances in the series mayhave a geometry or geometries selected to overcorrect the tootharrangement. For instance, one or more appliances may have a geometrythat would (if fully achieved) move individual teeth beyond the tootharrangement that has been selected as the “final.” Such over-correctionmay be desirable in order to offset potential relapse after therepositioning method has been terminated (e.g., permit movement ofindividual teeth back toward their pre-corrected positions).Over-correction may also be beneficial to speed the rate of correction(e.g., an appliance with a geometry that is positioned beyond a desiredintermediate or final position may shift the individual teeth toward theposition at a greater rate). In such cases, the use of an appliance canbe terminated before the teeth reach the positions defined by theappliance. Furthermore, over-correction may be deliberately applied inorder to compensate for any inaccuracies or limitations of theappliance.

The various embodiments of the orthodontic appliances presented hereincan be fabricated in a wide variety of ways. In some embodiments, theorthodontic appliances herein (or portions thereof) can be producedusing direct fabrication, such as additive manufacturing techniques(also referred to herein as “3D printing) or subtractive manufacturingtechniques (e.g., milling). In some embodiments, direct fabricationinvolves forming an object (e.g., an orthodontic appliance or a portionthereof) without using a physical template (e.g., mold, mask etc.) todefine the object geometry. Additive manufacturing techniques can becategorized as follows: (1) vat photopolymerization (e.g.,stereolithography), in which an object is constructed layer by layerfrom a vat of liquid photopolymer resin; (2) material jetting, in whichmaterial is jetted onto a build platform using either a continuous ordrop on demand (DOD) approach; (3) binder jetting, in which alternatinglayers of a build material (e.g., a powder-based material) and a bindingmaterial (e.g., a liquid binder) are deposited by a print head; (4)fused deposition modeling (FDM), in which material is drawn though anozzle, heated, and deposited layer by layer; (5) powder bed fusion,including but not limited to direct metal laser sintering (DMLS),electron beam melting (EBM), selective heat sintering (SHS), selectivelaser melting (SLM), and selective laser sintering (SLS); (6) sheetlamination, including but not limited to laminated object manufacturing(LOM) and ultrasonic additive manufacturing (UAM); and (7) directedenergy deposition, including but not limited to laser engineering netshaping, directed light fabrication, direct metal deposition, and 3Dlaser cladding. For example, stereolithography can be used to directlyfabricate one or more of the appliances herein. In some embodiments,stereolithography involves selective polymerization of a photosensitiveresin (e.g., a photopolymer) according to a desired cross-sectionalshape using light (e.g., ultraviolet light). The object geometry can bebuilt up in a layer-by-layer fashion by sequentially polymerizing aplurality of object cross-sections. As another example, the appliancesherein can be directly fabricated using selective laser sintering. Insome embodiments, selective laser sintering involves using a laser beamto selectively melt and fuse a layer of powdered material according to adesired cross-sectional shape in order to build up the object geometry.As yet another example, the appliances herein can be directly fabricatedby fused deposition modeling. In some embodiments, fused depositionmodeling involves melting and selectively depositing a thin filament ofthermoplastic polymer in a layer-by-layer manner in order to form anobject. In yet another example, material jetting can be used to directlyfabricate the appliances herein. In some embodiments, material jettinginvolves jetting or extruding one or more materials onto a build surfacein order to form successive layers of the object geometry.

Alternatively or in combination, some embodiments of the appliancesherein (or portions thereof) can be produced using indirect fabricationtechniques, such as by thermoforming over a positive or negative mold.Indirect fabrication of an orthodontic appliance can involve producing apositive or negative mold of the patient's dentition in a targetarrangement (e.g., by rapid prototyping, milling, etc.) andthermoforming one or more sheets of material over the mold in order togenerate an appliance shell.

In some embodiments, the direct fabrication methods provided hereinbuild up the object geometry in a layer-by-layer fashion, withsuccessive layers being formed in discrete build steps. Alternatively orin combination, direct fabrication methods that allow for continuousbuild-up of an object geometry can be used, referred to herein as“continuous direct fabrication.” Various types of continuous directfabrication methods can be used. As an example, in some embodiments, theappliances herein are fabricated using “continuous liquid interphaseprinting,” in which an object is continuously built up from a reservoirof photopolymerizable resin by forming a gradient of partially curedresin between the building surface of the object and apolymerization-inhibited “dead zone.” In some embodiments, asemi-permeable membrane is used to control transport of aphotopolymerization inhibitor (e.g., oxygen) into the dead zone in orderto form the polymerization gradient. Continuous liquid interphaseprinting can achieve fabrication speeds about 25 times to about 100times faster than other direct fabrication methods, and speeds about1000 times faster can be achieved with the incorporation of coolingsystems. Continuous liquid interphase printing is described in U.S.Patent Publication Nos. 2015/0097315, 2015/0097316, and 2015/0102532,the disclosures of each of which are incorporated herein by reference intheir entirety.

As another example, a continuous direct fabrication method can achievecontinuous build-up of an object geometry by continuous movement of thebuild platform (e.g., along the vertical or Z-direction) during theirradiation phase, such that the hardening depth of the irradiatedphotopolymer is controlled by the movement speed. Accordingly,continuous polymerization of material on the build surface can beachieved. Such methods are described in U.S. Pat. No. 7,892,474, thedisclosure of which is incorporated herein by reference in its entirety.

In another example, a continuous direct fabrication method can involveextruding a composite material composed of a curable liquid materialsurrounding a solid strand. The composite material can be extruded alonga continuous three-dimensional path in order to form the object. Suchmethods are described in U.S. Patent Publication No. 2014/0061974, thedisclosure of which is incorporated herein by reference in its entirety.

In yet another example, a continuous direct fabrication method utilizesa “heliolithography” approach in which the liquid photopolymer is curedwith focused radiation while the build platform is continuously rotatedand raised. Accordingly, the object geometry can be continuously builtup along a spiral build path. Such methods are described in U.S. PatentPublication No. 2014/0265034, the disclosure of which is incorporatedherein by reference in its entirety.

The direct fabrication approaches provided herein are compatible with awide variety of materials, including but not limited to one or more ofthe following: a polyester, a co-polyester, a polycarbonate, athermoplastic polyurethane, a polypropylene, a polyethylene, apolypropylene and polyethylene copolymer, an acrylic, a cyclic blockcopolymer, a polyetheretherketone, a polyamide, a polyethyleneterephthalate, a polybutylene terephthalate, a polyetherimide, apolyethersulfone, a polytrimethylene terephthalate, a styrenic blockcopolymer (SBC), a silicone rubber, an elastomeric alloy, athermoplastic elastomer (TPE), a thermoplastic vulcanizate (TPV)elastomer, a polyurethane elastomer, a block copolymer elastomer, apolyolefin blend elastomer, a thermoplastic co-polyester elastomer, athermoplastic polyamide elastomer, a thermoset material, or combinationsthereof. The materials used for direct fabrication can be provided in anuncured form (e.g., as a liquid, resin, powder, etc.) and can be cured(e.g., by photopolymerization, light curing, gas curing, laser curing,crosslinking, etc.) in order to form an orthodontic appliance or aportion thereof. The properties of the material before curing may differfrom the properties of the material after curing. Once cured, thematerials herein can exhibit sufficient strength, stiffness, durability,biocompatibility, etc. for use in an orthodontic appliance. Thepost-curing properties of the materials used can be selected accordingto the desired properties for the corresponding portions of theappliance.

In some embodiments, relatively rigid portions of the orthodonticappliance can be formed via direct fabrication using one or more of thefollowing materials: a polyester, a co-polyester, a polycarbonate, athermoplastic polyurethane, a polypropylene, a polyethylene, apolypropylene and polyethylene copolymer, an acrylic, a cyclic blockcopolymer, a polyetheretherketone, a polyamide, a polyethyleneterephthalate, a polybutylene terephthalate, a polyetherimide, apolyethersulfone, and/or a polytrimethylene terephthalate.

In some embodiments, relatively elastic portions of the orthodonticappliance can be formed via direct fabrication using one or more of thefollowing materials: a styrenic block copolymer (SBC), a siliconerubber, an elastomeric alloy, a thermoplastic elastomer (TPE), athermoplastic vulcanizate (TPV) elastomer, a polyurethane elastomer, ablock copolymer elastomer, a polyolefin blend elastomer, a thermoplasticco-polyester elastomer, and/or a thermoplastic polyamide elastomer.

Machine parameters can include curing parameters. For digital lightprocessing (DLP)-based curing systems, curing parameters can includepower, curing time, and/or grayscale of the full image. For laser-basedcuring systems, curing parameters can include power, speed, beam size,beam shape and/or power distribution of the beam. For printing systems,curing parameters can include material drop size, viscosity, and/orcuring power. These machine parameters can be monitored and adjusted ona regular basis (e.g., some parameters at every 1-x layers and someparameters after each build) as part of the process control on thefabrication machine. Process control can be achieved by including asensor on the machine that measures power and other beam parametersevery layer or every few seconds and automatically adjusts them with afeedback loop. For DLP machines, gray scale can be measured andcalibrated before, during, and/or at the end of each build, and/or atpredetermined time intervals (e.g., every n^(th) build, once per hour,once per day, once per week, etc.), depending on the stability of thesystem. In addition, material properties and/or photo-characteristicscan be provided to the fabrication machine, and a machine processcontrol module can use these parameters to adjust machine parameters(e.g., power, time, gray scale, etc.) to compensate for variability inmaterial properties. By implementing process controls for thefabrication machine, reduced variability in appliance accuracy andresidual stress can be achieved.

Optionally, the direct fabrication methods described herein allow forfabrication of an appliance including multiple materials, referred toherein as “multi-material direct fabrication.” In some embodiments, amulti-material direct fabrication method involves concurrently formingan object from multiple materials in a single manufacturing step. Forinstance, a multi-tip extrusion apparatus can be used to selectivelydispense multiple types of materials from distinct material supplysources in order to fabricate an object from a plurality of differentmaterials. Such methods are described in U.S. Pat. No. 6,749,414, thedisclosure of which is incorporated herein by reference in its entirety.Alternatively or in combination, a multi-material direct fabricationmethod can involve forming an object from multiple materials in aplurality of sequential manufacturing steps. For instance, a firstportion of the object can be formed from a first material in accordancewith any of the direct fabrication methods herein, then a second portionof the object can be formed from a second material in accordance withmethods herein, and so on, until the entirety of the object has beenformed.

Direct fabrication can provide various advantages compared to othermanufacturing approaches. For instance, in contrast to indirectfabrication, direct fabrication permits production of an orthodonticappliance without utilizing any molds or templates for shaping theappliance, thus reducing the number of manufacturing steps involved andimproving the resolution and accuracy of the final appliance geometry.Additionally, direct fabrication permits precise control over thethree-dimensional geometry of the appliance, such as the appliancethickness. Complex structures and/or auxiliary components can be formedintegrally as a single piece with the appliance shell in a singlemanufacturing step, rather than being added to the shell in a separatemanufacturing step. In some embodiments, direct fabrication is used toproduce appliance geometries that would be difficult to create usingalternative manufacturing techniques, such as appliances with very smallor fine features, complex geometric shapes, undercuts, interproximalstructures, shells with variable thicknesses, and/or internal structures(e.g., for improving strength with reduced weight and material usage).For example, in some embodiments, the direct fabrication approachesherein permit fabrication of an orthodontic appliance with feature sizesof less than or equal to about 5 μm, or within a range from about 5 μmto about 50 μm, or within a range from about 20 μm to about 50 μm.

The direct fabrication techniques described herein can be used toproduce appliances with substantially isotropic material properties,e.g., substantially the same or similar strengths along all directions.In some embodiments, the direct fabrication approaches herein permitproduction of an orthodontic appliance with a strength that varies by nomore than about 25%, about 20%, about 15%, about 10%, about 5%, about1%, or about 0.5% along all directions. Additionally, the directfabrication approaches herein can be used to produce orthodonticappliances at a faster speed compared to other manufacturing techniques.In some embodiments, the direct fabrication approaches herein allow forproduction of an orthodontic appliance in a time interval less than orequal to about 1 hour, about 30 minutes, about 25 minutes, about 20minutes, about 15 minutes, about 10 minutes, about 5 minutes, about 4minutes, about 3 minutes, about 2 minutes, about 1 minutes, or about 30seconds. Such manufacturing speeds allow for rapid “chair-side”production of customized appliances, e.g., during a routine appointmentor checkup.

In some embodiments, the direct fabrication methods described hereinimplement process controls for various machine parameters of a directfabrication system or device in order to ensure that the resultantappliances are fabricated with a high degree of precision. Suchprecision can be beneficial for ensuring accurate delivery of a desiredforce system to the teeth in order to effectively elicit toothmovements. Process controls can be implemented to account for processvariability arising from multiple sources, such as the materialproperties, machine parameters, environmental variables, and/orpost-processing parameters.

Material properties may vary depending on the properties of rawmaterials, purity of raw materials, and/or process variables duringmixing of the raw materials. In many embodiments, resins or othermaterials for direct fabrication should be manufactured with tightprocess control to ensure little variability in photo-characteristics,material properties (e.g., viscosity, surface tension), physicalproperties (e.g., modulus, strength, elongation) and/or thermalproperties (e.g., glass transition temperature, heat deflectiontemperature). Process control for a material manufacturing process canbe achieved with screening of raw materials for physical propertiesand/or control of temperature, humidity, and/or other process parametersduring the mixing process. By implementing process controls for thematerial manufacturing procedure, reduced variability of processparameters and more uniform material properties for each batch ofmaterial can be achieved. Residual variability in material propertiescan be compensated with process control on the machine, as discussedfurther herein.

Machine parameters can include curing parameters. For digital lightprocessing (DLP)-based curing systems, curing parameters can includepower, curing time, and/or grayscale of the full image. For laser-basedcuring systems, curing parameters can include power, speed, beam size,beam shape and/or power distribution of the beam. For printing systems,curing parameters can include material drop size, viscosity, and/orcuring power. These machine parameters can be monitored and adjusted ona regular basis (e.g., some parameters at every 1-x layers and someparameters after each build) as part of the process control on thefabrication machine. Process control can be achieved by including asensor on the machine that measures power and other beam parametersevery layer or every few seconds and automatically adjusts them with afeedback loop. For DLP machines, gray scale can be measured andcalibrated at the end of each build. In addition, material propertiesand/or photo-characteristics can be provided to the fabrication machine,and a machine process control module can use these parameters to adjustmachine parameters (e.g., power, time, gray scale, etc.) to compensatefor variability in material properties. By implementing process controlsfor the fabrication machine, reduced variability in appliance accuracyand residual stress can be achieved.

In many embodiments, environmental variables (e.g., temperature,humidity, Sunlight or exposure to other energy/curing source) aremaintained in a tight range to reduce variable in appliance thicknessand/or other properties. Optionally, machine parameters can be adjustedto compensate for environmental variables.

In many embodiments, post-processing of appliances includes cleaning,post-curing, and/or support removal processes. Relevant post-processingparameters can include purity of cleaning agent, cleaning pressureand/or temperature, cleaning time, post-curing energy and/or time,and/or consistency of support removal process. These parameters can bemeasured and adjusted as part of a process control scheme. In addition,appliance physical properties can be varied by modifying thepost-processing parameters. Adjusting post-processing machine parameterscan provide another way to compensate for variability in materialproperties and/or machine properties.

The configuration of the orthodontic appliances herein can be determinedaccording to a treatment plan for a patient, e.g., a treatment planinvolving successive administration of a plurality of appliances forincrementally repositioning teeth. Computer-based treatment planningand/or appliance manufacturing methods can be used in order tofacilitate the design and fabrication of appliances. For instance, oneor more of the appliance components described herein can be digitallydesigned and fabricated with the aid of computer-controlledmanufacturing devices (e.g., computer numerical control (CNC) milling,computer-controlled rapid prototyping such as 3D printing, etc.). Thecomputer-based methods presented herein can improve the accuracy,flexibility, and convenience of appliance fabrication.

FIG. 2 illustrates a method 200 for designing an orthodontic applianceto be produced by direct fabrication, in accordance with embodiments.The method 200 can be applied to any embodiment of the orthodonticappliances described herein. Some or all of the steps of the method 200can be performed by any suitable data processing system or device, e.g.,one or more processors configured with suitable instructions.

In step 210, a movement path to move one or more teeth from an initialarrangement to a target arrangement is determined. The initialarrangement can be determined from a mold or a scan of the patient'steeth or mouth tissue, e.g., using wax bites, direct contact scanning,x-ray imaging, tomographic imaging, sonographic imaging, and othertechniques for obtaining information about the position and structure ofthe teeth, jaws, gums and other orthodontically relevant tissue. Fromthe obtained data, a digital data set can be derived that represents theinitial (e.g., pretreatment) arrangement of the patient's teeth andother tissues. Optionally, the initial digital data set is processed tosegment the tissue constituents from each other. For example, datastructures that digitally represent individual tooth crowns can beproduced. Advantageously, digital models of entire teeth can beproduced, including measured or extrapolated hidden surfaces and rootstructures, as well as surrounding bone and soft tissue.

The target arrangement of the teeth (e.g., a desired and intended endresult of orthodontic treatment) can be received from a clinician in theform of a prescription, can be calculated from basic orthodonticprinciples, and/or can be extrapolated computationally from a clinicalprescription. With a specification of the desired final positions of theteeth and a digital representation of the teeth themselves, the finalposition and surface geometry of each tooth can be specified to form acomplete model of the tooth arrangement at the desired end of treatment.

Having both an initial position and a target position for each tooth, amovement path can be defined for the motion of each tooth. In someembodiments, the movement paths are configured to move the teeth in thequickest fashion with the least amount of round-tripping to bring theteeth from their initial positions to their desired target positions.The tooth paths can optionally be segmented, and the segments can becalculated so that each tooth's motion within a segment stays withinthreshold limits of linear and rotational translation. In this way, theend points of each path segment can constitute a clinically viablerepositioning, and the aggregate of segment end points can constitute aclinically viable sequence of tooth positions, so that moving from onepoint to the next in the sequence does not result in a collision ofteeth.

In step 220, a force system to produce movement of the one or more teethalong the movement path is determined. A force system can include one ormore forces and/or one or more torques. Different force systems canresult in different types of tooth movement, such as tipping,translation, rotation, extrusion, intrusion, root movement, etc.Biomechanical principles, modeling techniques, forcecalculation/measurement techniques, and the like, including knowledgeand approaches commonly used in orthodontia, may be used to determinethe appropriate force system to be applied to the tooth to accomplishthe tooth movement. In determining the force system to be applied,sources may be considered including literature, force systems determinedby experimentation or virtual modeling, computer-based modeling,clinical experience, minimization of unwanted forces, etc.

The determination of the force system can include constraints on theallowable forces, such as allowable directions and magnitudes, as wellas desired motions to be brought about by the applied forces. Forexample, in fabricating palatal expanders, different movement strategiesmay be desired for different patients. For example, the amount of forceneeded to separate the palate can depend on the age of the patient, asvery young patients may not have a fully-formed suture. Thus, injuvenile patients and others without fully-closed palatal sutures,palatal expansion can be accomplished with lower force magnitudes.Slower palatal movement can also aid in growing bone to fill theexpanding suture. For other patients, a more rapid expansion may bedesired, which can be achieved by applying larger forces. Theserequirements can be incorporated as needed to choose the structure andmaterials of appliances; for example, by choosing palatal expanderscapable of applying large forces for rupturing the palatal suture and/orcausing rapid expansion of the palate. Subsequent appliance stages canbe designed to apply different amounts of force, such as first applyinga large force to break the suture, and then applying smaller forces tokeep the suture separated or gradually expand the palate and/or arch.

The determination of the force system can also include modeling of thefacial structure of the patient, such as the skeletal structure of thejaw and palate. Scan data of the palate and arch, such as Xray data or3D optical scanning data, for example, can be used to determineparameters of the skeletal and muscular system of the patient's mouth,so as to determine forces sufficient to provide a desired expansion ofthe palate and/or arch. In some embodiments, the thickness and/ordensity of the mid-palatal suture may be measured, or input by atreating professional. In other embodiments, the treating professionalcan select an appropriate treatment based on physiologicalcharacteristics of the patient. For example, the properties of thepalate may also be estimated based on factors such as the patient'sage—for example, young juvenile patients will typically require lowerforces to expand the suture than older patients, as the suture has notyet fully formed.

In step 230, an arch or palate expander design for an orthodonticappliance configured to produce the force system is determined.Determination of the arch or palate expander design, appliance geometry,material composition, and/or properties can be performed using atreatment or force application simulation environment. A simulationenvironment can include, e.g., computer modeling systems, biomechanicalsystems or apparatus, and the like. Optionally, digital models of theappliance and/or teeth can be produced, such as finite element models.The finite element models can be created using computer programapplication software available from a variety of vendors. For creatingsolid geometry models, computer aided engineering (CAE) or computeraided design (CAD) programs can be used, such as the AutoCAD® softwareproducts available from Autodesk, Inc., of San Rafael, Calif. Forcreating finite element models and analyzing them, program products froma number of vendors can be used, including finite element analysispackages from ANSYS, Inc., of Canonsburg, Pa., and SIMULIA(Abaqus)software products from Dassault Systémes of Waltham, Mass.

Optionally, one or more arch or palate expander designs can be selectedfor testing or force modeling. As noted above, a desired tooth movement,as well as a force system required or desired for eliciting the desiredtooth movement, can be identified. Using the simulation environment, acandidate arch or palate expander design can be analyzed or modeled fordetermination of an actual force system resulting from use of thecandidate appliance. One or more modifications can optionally be made toa candidate appliance, and force modeling can be further analyzed asdescribed, e.g., in order to iteratively determine an appliance designthat produces the desired force system.

In step 240, instructions for fabrication of the orthodontic applianceincorporating the arch or palate expander design are generated. Theinstructions can be configured to control a fabrication system or devicein order to produce the orthodontic appliance with the specified arch orpalate expander design. In some embodiments, the instructions areconfigured for manufacturing the orthodontic appliance using directfabrication (e.g., stereolithography, selective laser sintering, fuseddeposition modeling, 3D printing, continuous direct fabrication,multi-material direct fabrication, etc.), in accordance with the variousmethods presented herein. In alternative embodiments, the instructionscan be configured for indirect fabrication of the appliance, e.g., bythermoforming.

Method 200 may comprise additional steps: 1) The upper arch and palateof the patient is scanned intraorally to generate three dimensional dataof the palate and upper arch; 2) The three dimensional shape profile ofthe appliance is determined to provide a gap and teeth engagementstructures as described herein.

Although the above steps show a method 200 of designing an orthodonticappliance in accordance with some embodiments, a person of ordinaryskill in the art will recognize some variations based on the teachingdescribed herein. Some of the steps may comprise sub-steps. Some of thesteps may be repeated as often as desired. One or more steps of themethod 200 may be performed with any suitable fabrication system ordevice, such as the embodiments described herein. Some of the steps maybe optional, and the order of the steps can be varied as desired.

FIG. 3 illustrates a method 300 for digitally planning an orthodontictreatment and/or design or fabrication of an appliance, in accordancewith embodiments. The method 300 can be applied to any of the treatmentprocedures described herein and can be performed by any suitable dataprocessing system.

In step 310, a digital representation of a patient's teeth is received.The digital representation can include surface topography data for thepatient's intraoral cavity (including teeth, gingival tissues, etc.).The surface topography data can be generated by directly scanning theintraoral cavity, a physical model (positive or negative) of theintraoral cavity, or an impression of the intraoral cavity, using asuitable scanning device (e.g., a handheld scanner, desktop scanner,etc.).

In step 320, one or more treatment stages are generated based on thedigital representation of the teeth. The treatment stages can beincremental repositioning stages of an orthodontic treatment proceduredesigned to move one or more of the patient's teeth from an initialtooth arrangement to a target arrangement. For example, the treatmentstages can be generated by determining the initial tooth arrangementindicated by the digital representation, determining a target tootharrangement, and determining movement paths of one or more teeth in theinitial arrangement necessary to achieve the target tooth arrangement.The movement path can be optimized based on minimizing the totaldistance moved, preventing collisions between teeth, avoiding toothmovements that are more difficult to achieve, or any other suitablecriteria.

In step 330, at least one orthodontic appliance is fabricated based onthe generated treatment stages. For example, a set of appliances can befabricated, each shaped according a tooth arrangement specified by oneof the treatment stages, such that the appliances can be sequentiallyworn by the patient to incrementally reposition the teeth from theinitial arrangement to the target arrangement. The appliance set mayinclude one or more of the orthodontic appliances described herein. Thefabrication of the appliance may involve creating a digital model of theappliance to be used as input to a computer-controlled fabricationsystem. The appliance can be formed using direct fabrication methods,indirect fabrication methods, or combinations thereof, as desired.

In some instances, staging of various arrangements or treatment stagesmay not be necessary for design and/or fabrication of an appliance. Asillustrated by the dashed line in FIG. 3 , design and/or fabrication ofan orthodontic appliance, and perhaps a particular orthodontictreatment, may include use of a representation of the patient's teeth(e.g., receive a digital representation of the patient's teeth 310),followed by design and/or fabrication of an orthodontic appliance basedon a representation of the patient's teeth in the arrangementrepresented by the received representation.

FIG. 4 is a simplified block diagram of a data processing system 400that may be used in executing methods and processes described herein.The data processing system 400 typically includes at least one processor402 that communicates with one or more peripheral devices via bussubsystem 404. These peripheral devices typically include a storagesubsystem 406 (memory subsystem 408 and file storage subsystem 414), aset of user interface input and output devices 418, and an interface tooutside networks 416. This interface is shown schematically as “NetworkInterface” block 416, and is coupled to corresponding interface devicesin other data processing systems via communication network interface424. Data processing system 400 can include, for example, one or morecomputers, such as a personal computer, workstation, mainframe, laptop,and the like.

The user interface input devices 418 are not limited to any particulardevice, and can typically include, for example, a keyboard, pointingdevice, mouse, scanner, interactive displays, touchpad, joysticks, etc.Similarly, various user interface output devices can be employed in asystem of the invention, and can include, for example, one or more of aprinter, display (e.g., visual, non-visual) system/subsystem,controller, projection device, audio output, and the like.

Storage subsystem 406 maintains the basic required programming,including computer readable media having instructions (e.g., operatinginstructions, etc.), and data constructs. The program modules discussedherein are typically stored in storage subsystem 406. Storage subsystem406 typically includes memory subsystem 408 and file storage subsystem414. Memory subsystem 408 typically includes a number of memories (e.g.,RAM 410, ROM 412, etc.) including computer readable memory for storageof fixed instructions, instructions and data during program execution,basic input/output system, etc. File storage subsystem 414 providespersistent (non-volatile) storage for program and data files, and caninclude one or more removable or fixed drives or media, hard disk,floppy disk, CD-ROM, DVD, optical drives, and the like. One or more ofthe storage systems, drives, etc may be located at a remote location,such coupled via a server on a network or via the internet/World WideWeb. In this context, the term “bus subsystem” is used generically so asto include any mechanism for letting the various components andsubsystems communicate with each other as intended and can include avariety of suitable components/systems that would be known or recognizedas suitable for use therein. It will be recognized that variouscomponents of the system can be, but need not necessarily be at the samephysical location, but could be connected via various local-area orwide-area network media, transmission systems, etc.

Scanner 420 includes any means for obtaining a digital representation(e.g., images, surface topography data, etc.) of a patient's teeth(e.g., by scanning physical models of the teeth such as casts 421, byscanning impressions taken of the teeth, or by directly scanning theintraoral cavity), which can be obtained either from the patient or fromtreating professional, such as an orthodontist, and includes means ofproviding the digital representation to data processing system 400 forfurther processing. Scanner 420 may be located at a location remote withrespect to other components of the system and can communicate image dataand/or information to data processing system 400, for example, via anetwork interface 424. Fabrication system 422 fabricates appliances 423based on a treatment plan, including data set information received fromdata processing system 400. Fabrication machine 422 can, for example, belocated at a remote location and receive data set information from dataprocessing system 400 via network interface 424.

The data processing aspects of the methods described herein can beimplemented in digital electronic circuitry, or in computer hardware,firmware, software, or suitable combinations thereof. Data processingapparatus can be implemented in a computer program product tangiblyembodied in a machine-readable storage device for execution by aprogrammable processor. Data processing steps can be performed by aprogrammable processor executing program instructions to performfunctions by operating on input data and generating output. The dataprocessing aspects can be implemented in one or more computer programsthat are executable on a programmable system, the system including oneor more programmable processors operably coupled to a data storagesystem. Generally, a processor will receive instructions and data from aread-only memory and/or a random access memory. Storage devices suitablefor tangibly embodying computer program instructions and data includeall forms of nonvolatile memory, such as: semiconductor memory devices,such as EPROM, EEPROM, and flash memory devices; magnetic disks such asinternal hard disks and removable disks; magneto-optical disks; andCD-ROM disks.

Palate Expanders

FIG. 5 illustrates an orthodontic appliance 500 comprising a palatalexpander portion 501 within the mouth of a patient. The appliance 500comprises a teeth engaging portion having a plurality of tooth-receivingcavities 502 configured to receive teeth. A gap 507 can extend betweenthe upper portion of the palate and the upper portion of appliance 500when placed in the mouth of the patient. The teeth engaging portion canbe similar to commercially available tooth repositioning appliancescomprising transparent shell portions to reposition teeth. The teethengaging portion can be configured to resiliently reposition thepatient's teeth 503. In particular, a palatal expander may apply forcegenerating orthodontic forces 505 against groups of one or more teeth onopposite sides of a patient's mouth, in order to cause the patient'spalate 504 to expand. These forces may be caused by an expansion 506 ofthe expander portion 501. An extension portion 506 can extend betweenthe expander portion 501 and the teeth engaging portion comprisingcavities 502 in order to couple the expander portion 501 with the teethengaging portion. Among other outcomes, this expansion of palate 504 maycoincide with an increase in distance between teeth 503 on oppositesides of the patient's mouth. Palate expansion typically requiresstronger forces and larger-scale movements than those typically used fororthodontic movement of single teeth, presenting unique challenges indesigning palate expanders. Among the challenges that must be overcomeare the design of a palate expander capable of providing strong forceswithout damage as well as preventing or minimizing distortions, such asmay cause uncomfortable upward pressure between the expander portion 501and the palate 504.

In particular, the force 505 applied to the teeth 503 may tend to causean undesired tipping movement, in which the teeth 503 are tiltedoutwards as a reaction to the applied force from the aligner. To reducetipping, the extension portion 506 may be shaped to contact portions ofthe patient's palate, such at locations 508 and 509, so as to applyforce to the palate directly in addition to the forces applied to theteeth 503. Optionally, an implantable device such as a temporaryanchorage device (TAD) may be provided in the patient's palate, such asat locations 508 and 509. The TAD can be embedded into or attached tothe bone of the patient's palate so as to transmit force directly fromthe appliance to the patient's palate. The appliance can be shaped withsurface portions configured to receive the TAD, such as a hook or socketfor example. The locations of points 508 and 509 can be varied as neededto distribute appropriate force; for example, the locations can beselected by a treating professional or a computer model of the patient'spalate and dentition. In some embodiments, the TADs are located on theroof of the palate on opposite sides of the suture, and the appliance isshaped to engage the TADs to apply a palate-expanding force. Multiplepoints of contact, including continuous contact surfaces, may also beused for direct palate contact and/or contact with a TAD. This allowsthe total palate-separating force to be distributed over multiplesurfaces, decreasing the amount of force any particular surface mustbear. For example, the force on the teeth 503 can comprise only aportion of the total palate expanding force, reducing the likelihood ofinducing tipping movement.

An orthodontic appliance 500 comprising a palatal expander shaped toapply force both to the palate and to the teeth can be readily designedfor fabrication using the methods disclosed herein. For example, inmethod 200, step 220, the force system can include forces applied toboth teeth and palate areas to induce a palatal expansion. In step 230,a fabrication design for extension portion 506 can include materialshaped to contact portions of the palate along the left and/or rightarching parts of the palate, such as around areas 508 and 509 of thepalate, for example. Contact to the top of the palate may be limited inthe palate-expansion forces it can apply, while potentially causingdiscomfort to the patient. Accordingly, contact between the top of thepalate and the appliance when worn is not required. Thus, while in somecases, the appliance can be shaped to contact to the top of the palate,the appliance can also be shaped to provide a gap 507. This gap need notinhibit contact between the lateral portions of the palate and theappliance, such that palatal expansion forces can be applied to thesides of the palate without requiring contact with the top of thepalate. The appliance can be shaped such that contact areas 508 and 509are spread out over a large area of the palate, applying more uniformpressure across the contact areas while applying less localized pressureto the palate when the appliance is worn.

Direct fabrication allows the use of a wide range of materials andstructures, which may be combined in a variety of ways when designingappliance structures such as palate expanders In some cases, traditionalstructures used in palate expanders such as manually-adjusted screws maybe directly fabricated as well as augmented with further structures asdescribed herein. In some cases, traditional structures such as screwsor springs may be used in the appliances disclosed herein without beingdirectly fabricated. Alternatively, palate expanders may be fabricatedwithout the need for manual adjustments, for example by incorporating,within the expander portion 501, rigid materials that expand whencontacted with saliva, such as hydrophilic polymers, for example. Othermaterials with similar expansion properties, such as high rigidity andswelling capacity, may be selected to customize the expansion, as willbe appreciated by a person of ordinary skill in the art. In some cases,expander portion 501 can comprise a thermoplastic or thermoset material,for example.

FIG. 6 illustrates a top view of an appliance 600. Appliance 600 maycomprise many of the features and structures of appliance 500, forexample. Appliance 600 comprises a palate expander portion 601, a shell602, and an extension structure 603 joining the two together. Expansionof palate expander 601 provides force generating forces on shell 602,transmitted by extension structure 603. When worn by a patient, this maycause an expansion of a patient's palate, as illustrated incorresponding appliance 500 in FIG. 5 . In some embodiments, appliance600 may be fabricated as a single structure, wherein palate expander601, shell 602, and extension structure 603 may comprise differentmaterials. In some embodiments, palate expander 601 may connect directlyto shell 602, omitting extension structure 603. In some embodiments,palate expander 601 may comprise a plurality of materials, andadditionally or alternatively, shell 602 and extension structure 603 mayeach also comprise one or more materials. The size, structure, andmaterials of palate expander 601, shell 602, and extension structure 603may be varied to customize the force generating force produced. Infurther embodiments, palate expander 601, shell 602, and extensionstructure 603 may comprise the same material; for example, in some casesin which palate expander 601 comprises a fabricated spring or screwstructure.

In some embodiments, palate expander 601 may comprise a material thatexpands upon contact with a patient's saliva, permitting it tospontaneously begin applying force after being placed in a patient'smouth. The amount of force applied will depend on variables that may becontrolled during fabrication, such as the size of the palate expander601 and choice of material from which it is fabricated. Generally,larger palate expanders may cause larger forces, and more forcegenerating materials may likewise generating larger forces. The size ofthe palate expander may be varied during fabrication, for example bymaking it larger in a horizontal axis while making extension structure603 correspondingly shorter in that axis. The expansiveness of thematerial comprising palate expander 601 may be varied in a variety ofways, such as by switching to a material of different expansiveness orby employing a plurality of materials that expand differently. Forexample, a palate expander made of composite material uniformlycomprising equal amounts of force generating and non-force generatingpolymer will provide less force than a similar palate expander madeentirely of the force generating polymer Similar effects can begenerated using other non-polymer materials. In general, the force maybe tuned as desired by varying the proportions of different polymers orother materials in this manner. In the case of polymers, materialexpansion can also be controlled by choosing polymers with differentamounts of cross-linking, with more cross-linking leading to smalleramounts of expansion.

Another consideration when designing a palate expansion appliance is theavoidance of upward pressure on the patient's palate. If a palateexpander expands too much in a vertical direction, it may put pressureon the patient's palate, which may prove uncomfortable. Horizontalexpansion may also indirectly cause uncomfortable pressure in somecases, such as when it causes upward flexing of the appliance. Thematerial properties of a fabricated palate expander may be designed soas to relieve this potential problem.

FIG. 7 illustrates an appliance 700 which has been fabricated so as toinhibit contact with and avoid upwards pressure on a patient's palate,with a gap extending between the upper portion of the palate and theupper portion of the appliance as described herein. The palate expanderappliance 700 comprises a palate expander 701 comprising a plurality ofmaterials, arranged into a plurality of layers. As illustrated, theplurality of layers comprises an upper layer 702 that is configured toinhibit contact with the patient's palate and a lower layer 703underneath. These two layers are both attached to appliance shell 704,wherein the connection may be direct or may comprise an extensionstructure as described herein. The materials of layers 702 and 703 arechosen to expand at different rates—for example, upper layer 702 maycomprise a material with lower swelling capacity than the material oflayer 703. This difference between materials may, for example, becontrolled by fabricating the different layers from polymeric materialwith different amounts of cross-linking, thereby varying the swellingcapacity. For example, materials with more cross-linking can haveenhanced stiffness, and thereby resist swelling, whereas materials withless cross-linking can have reduced stiffness, thereby increasingswelling. The effect of this difference is illustrated by forces 712 and713, wherein forces 713 are greater in magnitude than forces 712. Thesedifferent magnitudes of force cause a bending of the appliance 714 thatcan relieve upwards pressure that might otherwise push on the top of thepalate of the patient. The bending 714 can also be used to apply contactforces on the lateral sides of the palate, such that force on the roofof the mouth is diminished while force on the sides of the palate and onthe teeth is increased, thereby providing a combined palate expansionforce. The magnitude of palate contact force can be adjusted byselecting an appropriate shape and thickness of upper layer 702 near thecontact points, as well as appropriately selecting lower layer 703 toprovide the desired expansion movement. Further layered structures maybe contemplated, comprising a plurality of layers of different swellingcapacities. Alternatively or additionally, the layered structure mayvary its swelling capacity continuously along axes, such as a verticalaxis and/or a horizontal axis.

Further embodiments are shown in FIGS. 8A-E, which illustrate a few ofthe many optional palate expander structures which may be fabricatedusing direct fabrication techniques as described herein. The structuresdepicted in FIGS. 8A-E may be fabricated as part of an appliance furthercomprising tooth-receiving structures such as concavities. Theseembodiments show directly fabricated resilient structures configured tourge teeth on opposite sides of the arch away from each other. The toothreceiving engagement structures comprising concavities can be shaped toreceive teeth on the lingual side closer to the gingival portion thanthe occlusal portion. The appliances may comprise interproximalengagement structures to extend at least partially into interproximalspaces of the patient's teeth to improve retention. In many embodiments,these appliances can be retained on the patient's teeth with a lowprofile configuration without extending to both sides of each of theteeth. These appliances can be configured to provide a gap as describedherein.

FIG. 8A illustrates an appliance with palatal expander comprising adirectly fabricated spring structure 801. The palatal expander is shownplaced on the patient's teeth. The spring structure 801 comprises aplurality of compressible structures 802. When the appliance is insertedinto a patient's mouth, the compressible structures 802 are compressed,storing elastic potential energy. This stored potential energy resultsin an outward force to induce a palate expansion.

FIG. 8B illustrates an appliance with palatal expander comprising adirectly fabricated echelon-patterned and/or chevron patterned springstructure 811. The palatal expander is shown placed on the patient'steeth. The echelon structures comprising echelon-patterned springstructure 811 may be directly fabricated out of compressible materialthat will bend when placed in the patient's mouth. This bending storeselastic potential energy that results in an outward force to induce apalate expansion.

FIG. 8C illustrates an appliance with palatal expander comprising afabricated structure 821 comprising compressible curved portions 822.The palatal expander is shown placed on the patient's teeth. The curvedstructures 822 may be fabricated out of compressible material that willbend when placed in the patient's mouth. This bending stores elasticpotential energy that results in an outward force to induce a palateexpansion.

FIG. 8D illustrates an appliance with palatal expander comprising afabricated jack structure 831 comprising compressible hinged arms 832.The palatal expander is shown placed on the patient's teeth. Oppositeends of hinged arms 832 are connected by an elastic band 833, applyingan inward force 835 to opposite ends of the arms together. This inwardforce produces a motion as hinged arms rotate about hinges 834, whichmay be fabricated as part of structure 831. An outward force 836 resultsas the structure expands in the image's horizontal axis whilecompressing in the image's vertical axis. Force can be applied at thehinges, for example using a rubber band, to compress the jack structureand apply a palate-expanding force.

The force generating components disclosed herein can generate forcesbased on a target palatal displacement. For example, an amount ofpalatal expansion can be selected, and the force generating componentcan be fabricated such that an expansion force is generated when theappliance is worn, so long as the amount of palatal expansion is lessthan the target palatal displacement. Thus, an appliance can generatepalatal expansion forces without causing excessive expansion. In somecases, the target palatal displacement can be adjustable; for example,adjustable screws, springs, bands, or other components can be adjustedto change the size of the palatal expander, thereby changing the targetpalatal displacement. An adjustable palatal expander can be used togenerate a slow palatal expansion, for example.

FIG. 8E illustrates an appliance with palatal expander comprising amaterial that expands upon contact with human saliva. The palatalexpander is shown placed on the patient's teeth. Outer portions 841 ofthe appliance are comprises a rigid material that does not expand, whilean inner portion such as central portion 842 comprises a rigid materialwith a high swelling capacity such that it expands within a patient'smouth as it absorbs water from a patient's saliva. The expansion causesoutwards forces 843 that may be used to induce a palate expansion. Asdiscussed above, in some embodiments, central portion 842 comprises aplurality of layers or a material with continuously varied swellingcapacity. Alternatively or in combination, the inner portion such ascentral portion 842 comprises an elastic material capable of beingcompressed upon insertion to generate the force to the teeth to expandthe palate.

Although specific resilient spring structures are shown, the materialcan be shaped with structures such as voids to provide flexibility andcompressibility to the material, similar to closed cell foam and opencell foam to provide a compressible force generating structure.Alternatively or in combination a plurality of resilient structures asdescribed can be formed on a small scale, for example no more than about2 mm across, in order to provide the force generating portion.Furthermore, the forces produced by the appliances disclosed herein canbe varied by changing the size, shape, mass, and elasticity of thematerials used in the expanders, individually or in combination.

In some embodiments, aligners and palatal expanders may be directlyfabricated as separate components to be fit together later for use. Thepalate expander comprises a force generating component as disclosedherein and the aligner comprises a teeth engagement structure asdisclosed herein. The separate components may comprises correspondingengagement structures that allow the components to fit together and holdthe aligner and palate expander together when placed in the mouth of thepatient. The corresponding engagement structures can be configured inmany ways and may comprise one or more of locking structures, aprotrusion sized to extend into a receiving structure such as a recess,nested structures or locking structures. The aligner and plate expandermay comprise corresponding shape profiles that allow the correspondingstructures of the palate expander to aligner to fit together and be heldin place. In some instances, the corresponding structures can beconfigured for the engagement structures to gently snap in place, forexample. The user can be provided with a plurality of pieces to snap inplace over the course of a treatment plan of palate expansion, forexample.

Similarly, each of the palate expander and aligner can optionally becomposed of multiple, separately fabricated parts. For example, analigner can comprise a left and right portion to fit the left and rightdental arches, or left, right, and center portions to fit respectiveleft, right, and central teeth of an arch. These portions can befabricated as a single unit that can be separated and reattached, orthey can be fabricated separately for attachment thereafter. Similarly,the palate expander can be fabricated in one, two, three, or moreseparate parts that can be joined together, such as with the joiningmethods disclosed herein. In some cases, for example, each part, orcertain parts, can be fabricated from different materials so as topossess different properties such as stiffness.

FIG. 9A illustrates a removable palatal expander 900 fabricated to matewith an orthodontic appliance. The palatal expander 900 comprises anarch component 901 fabricated from elastic material to fit the palate ofa patient. The material may be fabricated to be larger than thepatient's palatal region, so that it compresses when worn, permitting anoutward force to be applied to a patient's teeth. The palatal expander900 further comprises a ridged portion 902 on each side designed toconform to the surface of an orthodontic appliance. The rigid portion902 may comprises protrusions sized and shaped to extend towardinterproximal the space of the teeth when engaging correspondingstructures of the teeth engaging appliance. In order to secure thepalatal expander to an orthodontic appliance, indentations 903 may belocated in the ridged portion 902 configured to mate with protrusions onthe appliance.

FIG. 9B illustrates part of an aligner 910 designed to mate with apalatal expander as shown in FIG. 9A. The aligner 910 comprises aplurality of teeth engagement structures comprising a plurality of teethreceiving cavities 911 sized and shaped to engage the teeth for palateexpansion. The aligner comprises plurality of tooth-receiving cavities911, as well as a labial contour 912. The labial contour 912 matches thecorresponding ridged portion 902 of the palatal expander. The teethengaging aligner component further comprises protrusions 913 configuredto engage, for example mate, with the corresponding indentations 903 ofthe palatal expander 900. The protrusions 913 can be located on a labialside of the teeth. The teeth engaging aligner component may comprisereceiving structures shaped to receive the protrusions of the rigidportion 902 of the arch component 901. This arrangement allows thepalatal expander 900 and the aligner 910 to hold together, for exampleto securely mate together. The aligner 910 can be configured to moveteeth in accordance with a treatment plan as described herein. The archcomponent 901 can be configured to move the palate in accordance with apalate expansion plan.

The teeth engagement structures that couple to the teeth can beconfigured in many ways. Although an aligner is shown, other structuresas described herein can be used to engage the teeth and couple to thepalate expander in order to engage the teeth. In some cases, theocclusal surface above the teeth receiving cavities can be shaped tosimulate the occlusal surfaces of teeth, as shown in FIG. 9C, showing asurface with varying height similar to that of ordinary tooth surfaces.Alternatively, portions of the occlusal surfaces of some or all teethreceiving cavities can be provided with a flatter surface. By supplyingupper and lower appliances with such flattened surfaces, the respectiveupper and lower arches can avoid engaging, allowing the arches to movemore freely. For example, if the occlusal surfaces of appliances alongthe left and right molars of each arch are substantially flattened, theleft and right arches can move more freely in lateral directions. Thus,for example, the expansion of the palate will be less inhibited by theengagement of the upper and lower arches, allowing less force to beneeded.

FIG. 9C show a picture of a directly fabricated orthodontic appliance920 comprising both a palatal expander 900 and an aligner 910. Thepalatal expander and aligner are made of different materials, with thepalatal expander capable of flexing when worn to store elastic energy,thereby applying force to a patient's teeth. The palate expandercomponent comprises an unloaded free standing configuration with theengagement structures such as protrusion having a separation distance onopposing sides of the expander sized larger than correspondingstructures of opposing sides of the arch of the aligner.

A 3D computer model 930 of appliance 920, which may for example begenerated when designing an orthodontic appliance according to methods200 or 300, is illustrated in FIG. 9D. A person of ordinary skill in theart can use computer modeling and experimentation to determine theforces to the teeth appropriate for palate expansion, and determine thesize, shape and material as described herein. The palate expandercomponent can be sized to inhibit or avoid contact with part or all ofthe palate in response to an oral scan or dental impression to generatethree dimensional profile data of the mouth as described herein. Thepalate expander component can be also be sized to selectively contactportions of the palate to apply palate-expanding forces, which may bedistributed over parts of the left and right palatal arches of a patientso as to decrease load on the teeth of the patient. The amount of forceapplied by appliance 920 is affected by the ridges illustrated in thecenter of the arch. The ridges on the appliance increase the stiffnessof the expander, which can be used to vary the expansion force applied.For example, adding thick ridges can produce a stiff arch that appliesforces over a short range, whereas thinner or missing ridges can producea more resilient shape that applies forces over a longer range.

FIG. 10 shows a design of an orthodontic appliance 1000 comprising aplastic aligner component 1001 and a metallic palatal expander 1002. Theuse of metal materials offer a number of advantages, such as greaterapplicable force, lack of stress relaxation, durability, corrosionresistance, and easy sterilization. Biocompatibility is also readilyachieved, since the use of metallic material in orthodontics is alreadyused in the dental industry, and the selection of appropriate metalswill be apparent to one of ordinary skill in the art. Metallic alignersmay be usefully fabricated using direct fabrication techniques such asDirect Metal Laser Sintering (DMLS), Electon-Beam Sintering, orSelective Laser Sintering, and in some cases may be fabricated directlyalong with a directly fabricated plastic aligner component. Similarly,multiple direct fabrication techniques may be used in combination, suchas by fabricating separate parts using separate techniques, such thatthe parts can be assembled into an appliance. The force applied byorthodontic appliance 1000 can be readily controlled by the thicknessand topology of the metallic expander 1002. For example, the metallicexpander 1002 comprises an arch with a circular hole, such that theamount of metal is less than would be present in a solid metallic arch.The expanding force is correspondingly reduced. By varying the size orshape of the hole of expander 1002, the expanding force can be increasedor decreased as needed; similarly, the thickness of the metal can bevaried, with thinner metal arches applying less force. The shape andnumber of holes can also be varied to tune the force; for example,shapes such as those illustrated in FIGS. 8A-8D can be employed.

A further expander design can employ a shape-memory material such as ashape-memory alloy or a shape-memory polymer that responds totemperature by altering its shape. The appliance can be prepared suchthat the expander has a first shape at a cold temperature, such as roomtemperature, and a second shape at warm temperature, such as human bodytemperature. The first shape can be selected to fit in a patient's mouthwithout applying significant expanding forces, while the second shapecan be selected to have a larger width than the first shape, such thatat a warmer temperature, the expander applies an outwards force on theteeth to expand the palate and/or the arch of the patient. Accordingly,the appliance can be placed in the mouth at room temperature withoutapplying excessive force, and then increase force continuously as theappliance heats to body temperature in the mouth.

Arch Expanders

The appliances disclosed herein, such as arch expanders for example, mayhave a stiff inner component and a soft outer component. The archexpander may comprise adjacent stiff portions extending in mesial distaldirections with a gap extending therebetween. The gap may have a springor other expansion device, e.g. polymer to urge opposing blocks of teethagainst each other. Upon compression shown with arrows, the forcegenerating structure of the gap can urge the adjacent sections apart tomove the teeth. Embodiments can have soft material extending aroundcircumference of teeth to provide placement. Exposed occlusal surfacecan provide improved inter digitation with tooth movement. This archexpander can also be used to align teeth.

The force generating structure can be built in and directly fabricated,for example as an expander with spring feature at the gap in stiffelongate portions to cause expansion. The distal teeth may compriseanchoring molars to facilitate movement of the anterior teeth on anopposite side of the gap comprising the expandable structure. The archcan be expanded with increasing separation of the elongate stiffsegments having the gap extending therebetween.

FIG. 11 illustrates a variety of different arch expander designs thatmay be incorporated into an orthodontic appliance, for example whendesigning an appliance in method 200. Arch expanders 1111, 1121, and1131 are shown incorporated into orthodontic appliances 1110, 1120, and1130 respectively. Appliances 1110, 1120, and 1130 each comprisetooth-receiving structures 1112, 1122, and 1132, respectively, such ascavities, designed to receive one or more of teeth 1113, 1123, and 1133,respectively. As illustrated, tooth-receiving structures 1112, 1122, and1132 may comprise a soft material, including possibly a soft clearmaterial. As illustrated, arch expanders 1111, 1121, and 1131 maycomprise a rigid material, which typically need not be clear, but mayoptionally be clear as well. The tooth-receiving structures 1112, 1122,and 1132 serve to hold appliances 1110, 1120, and 1130 on teeth 1113,1123, and 1133, respectively, allowing respective arch expanders 1111,1121, and 1131 to apply tooth moving forces such as arch expandingforces.

Direct fabrication of the arch expander allows improved fit and canprovide more accurate control of the forces to the teeth. The teethengagement structures of the stiff portion can extend into interproximalspaces of the teeth to improve fit and force coupling, for example.

Typically, an arch expander will be used to expand a dental archcomprising a plurality of teeth, such as teeth 1113. This expansion maycomprise a movement of a plurality of teeth in different directions; forexample, teeth on opposite medial sides of the mouth may be moved apart.Alternatively or additionally, posterior and anterior teeth may be movedaway from each other, so that the overall shape of the dental arch ischanged. This type of movement may be useful, for example, in thereduction of tooth crowding, or for other suitable purposes.

To accomplish the expansion of a dental arch, significant arch expandingforces may be used between one or more groups of teeth, in order to pushthem in different directions. The rigid material of arch expanders 1111,1121, and 1131 may be exploited to apply arch expanding forces. In someembodiments, an arch expander such as arch expander 1111 may be brokeninto different segments, separated by gaps 1114. As illustrated, forcesmay be applied between the separate segments, for example, usingmaterial inserted into the gaps 1114. In some embodiments, the gaps maybe bridged by one or more screws, which may be rotated in one directionto drive the segments of arch expander 1111 apart, or in the otherdirection to pull the segments together. The screws may be fabricated aspart of the appliance fabrication process, or installed separately usingknown machining techniques.

In some embodiments, springs may be installed to connect across the gaps1114, to apply spring forces on arch expander 1111. Depending on theproperties of the springs, such as spring elasticity, connection pointsof the springs to arch expander 1111, and spring rest length, the forcesapplied by the springs may be varied, optionally including forcestending to push segments apart and/or to pull them together, as desired.The springs may in some cases be fabricated separately and attached tothe arch expander 1111 and in some cases may be fabricated along withthe arch expander. A combination of springs fabricated separately and aspart of the arch expander fabrication process may also be used, asdesired. Additionally or alternatively, structures such as bars mayconnect one or more of the segments of arch expander 1111 to applyforce. These bar structures may likewise be fabricated as part of thearch expander 1111 or attached separately.

In some embodiments, an arch expanding force may be exerted betweensegments by fabricating arch expander 1111 with gaps 1114 filled with acompressible material. By designing the compressible material in thegaps 1114 to have a longer rest length than the gaps would otherwise bewhen the appliance 1110 is worn, an arch expanding force may be appliedas the compressed material in the gaps 1114 pushes outward on thesegments of arch expander 1111.

In some embodiments, rigid material in gaps 1114 may be designed so thatit changes its properties in response to being placed in a patient'smouth. For example, the material may expand in response to contact withthe patient's saliva, such as may be the case in materials such ashydrophilic polymers, for example. Suitable materials for use in thismanner may exhibit both high rigidity and swelling capacity. Thisexpansion may be tailored by varying the properties of the material,including the amount of expansion per unit volume and the shape and sizeof the gaps 1114, as well as the fraction of the gaps in which thematerial is placed. For example, larger gaps 1114 filled with materialwith higher swelling capacity may provide more arch expanding force,because the amount of arch expansion force that may be caused bymaterial filling the gaps 1114 grows in proportion to the size of thegaps, as well as to the fraction of the gaps (along the lingual-buccaland/or vertical directions) that has been filled.

A further use of material that expands in response to contact with apatient's saliva is to incorporate the material continuously throughouta solid arch expander. Arch expanders 1121 and 1131 may comprise theexpandable material for example. This design of the arch expander allowsfor nearly arbitrary control over the forces applied to teeth 1123 or1133. For example, if one or more particular teeth are to be singled outfor greater applied force, additional expandable material may be addedon one side of the one or more teeth, wherein the extra expansion ofthat material may apply a greater force to push the one or more teethaway from the material. The distribution of material may be chosen asdesired to apply a wide range of customizable forces on teeth 1123 or1133. This may be used, for example, to guide the teeth individually orin independent groups along a desired trajectory, while expanding thedental arch, for example. Further optional combination may be made withmaterials having different degrees or rigidity or of swelling capacityalong different axes to enable further customization of available forcescomprising a plurality of magnitudes and a plurality of directions oneach of a plurality of teeth.

Because direct fabrication allows the use of a plurality of differentmaterials in an appliance, the material of the tooth-receivingstructures may be chosen independently of the material of the archexpander. Thus, for example, tooth-receiving structures may comprisesoft and/or clear material whereas the arch expander may comprise hardand/or non-clear material. Furthermore, the tooth-receiving structuresthemselves may be made of more than one material, wherein a first and asecond set of tooth-receiving structures comprise a first and a secondmaterial. For example, tooth-receiving structures configured to receivemolars may be fabricated with a different material than those configuredto receive incisors.

The tooth-receiving structures may also be designed to engage differentteeth in many ways. For example, appliance 1110 comprisestooth-receiving structures 1112 that cover the occlusal surfaces oftheir respective teeth, whereas appliance 1120 comprises tooth-receivingstructures 1122 that extend substantially around and may surround theouter portion of their respective teeth while leaving the occlusalsurfaces uncovered. These two options may be combined: for exampleappliance 1130 comprises tooth-receiving structures 1132 of both types,each engaging a respective set of teeth. The tooth-receiving structuresmay be configured as needed to engage and anchor to their respectiveteeth, enabling tooth moving forces such as arch expanding forces to beapplied, as by arch expanders 1111, 1121, and 1131.

The exposed occlusal surfaces of the teeth can encourage movement of theteeth to have better occlusion with opposing teeth on an opposite arch.Alternatively, the material on the occlusal surfaces can be sufficientlythin to urge the teeth into appropriate alignment with teeth on theopposing arch.

FIG. 12 illustrates a further embodiment in which an appliance 1200 maybe fabricated with an arch expander comprising a connective portion 1201to apply forces between distant teeth. The appliance 1200 comprises apolymeric shell 1202 coupled to a connective portion 1201 at locations1203 and 1204, each location being near one or more distanttooth-receiving structures. The connective portion 1201 allows thetransmission of force between teeth at or near locations 1203 and 1204,for example, by applying elastic forces to cause an expansion orcontraction of connective portion 1201. Connective portion 1201 may bedesigned to customize the forces it applies in various ways. Examples ofdesign choices of connective portion 1201 include but are not limited tosprings, bars, compressible polymer, or polymer that expands uponcontacting saliva. Any of these nonexclusive options may be exercised byfabricating the corresponding structure directly, using fabricationtechniques as disclosed herein. In the case of direct fabrication, theappliance 1200 may be fabricated as a whole, including polymeric shell1202, connective portion 1201, and their joining points 1203 and 1204.Connective portion 1201 may be used on its own to supply an archexpansion force, or it may be combined with other arch expanders such asarch expanders 1111, 1121, or 1131, and any of these may additionally becombined with further orthodontic structures as will be apparent to oneof ordinary skill in the art.

FIG. 13 illustrates an aligner design that may be used in conjunctionwith the connective portion illustrated in FIG. 12 to guide a toothmovement. The aligner 1300 comprises an orthodontic appliance with aplurality of tooth-receiving cavities 1303. The appliance comprises aforce generating portion that applies an arch expanding force 1302. Theforce generating portion can be the connective portion illustrated inFIG. 12 , for example; in alternative embodiments, the force generatingportion can be one or the embodiments illustrated in FIG. 11 , or inFIGS. 15-16 , for example. The aligner comprises a flexible retentionportion 1304 that allows movement of the received teeth of the arch inresponse to force from the force generating portion. The aligner furthercomprises a stiff retention portion 1301 that resists movements of thenearby teeth, thereby resisting movement of a first plurality of teethwhile allowing movement of a second plurality of teeth. For example, thestiff retention portion 1301 can be arranged to inhibit a rotationalforce about a tooth, such as a canine tooth for example. The stiffretention portion can also resist linear translations, such that toothmoving forces can be distributed selectively across the teeth of thearch. The stiff retention portion reduces the tooth-moving force appliedto nearby teeth, so that teeth not near the stiff retention portionexperience relatively more force. This permits a controlled movement ofportions of the dental arch; for example, the molars may be moved in anoutwards direction of the arch expanding force 1302 while movement ofthe canines and incisors is reduced.

FIG. 14A illustrates an example of an appliance having an anterior ridgearch element, according to embodiments. FIG. 14A provides an appliance1400 having a shell 1401 with a ridge 1405 thereon to provide additionalrigidity and/or palate expansion force. The anterior ridge 1405 is asmall ridge on lingual side of the arch. It may be used to increasestructural integrity of the appliance in the transverse directionbetween the two ends of the jaw. For example, the anterior ridge archelement can provide a stiff retention portion that resists movement ofnearby teeth, while allowing movement of other teeth, or causing a firstplurality of teeth to move as a unit by providing a stiff connectionbetween the corresponding teeth receiving cavities. In some embodiments,the lingual ridge feature may run along one or more portions of or theentire span of the arch. The cross sectional geometry of the lingualridge can be varied uniformly or non-uniformly along its length toprovide additional rigidity and/or force to adjust the palate.

FIG. 14B illustrates an example of an appliance having a rib feature,according to embodiments. FIG. 14B provides an appliance 1400 that hasone or more rib features 1407 on the surface of the shell 1402. Thesefeatures are areas that are thicker than other portions of the appliancebody thickness and therefore provide additional rigidity and/or force.The rib portions can be used to provide a stiff retention portion toresist local tooth movement while allowing movement of other teethreceived by a flexible retention portion, for example.

Additionally, the ribs are elongate shapes that can be oriented indifferent directions along the surface of the shell 1402. This enablesthem to provide forces in specialized directions to control the forcesprovided to the teeth from the appliance with precision. In theillustrated embodiment, of FIG. 14B, the ribs have been configured in aparticular geometry to provide added rigidity to the posterior sectionof the dental appliance.

For example, in some embodiments, a rib feature can be positioned in thebuccal and/or lingual sections between the cavities for the crowns tostrengthen the appliance in the transverse direction, so individualteeth can be moved as a segment. In a mixed dentition case, if a primarytooth is lost during treatment, such an embodiment can help preserve thearch expansion force, since the posterior section is being expanded as asegment.

In some embodiments, teeth engaging structures and force generatingcomponents as described herein can be directly fabricated as separatecomponents and sized and shaped to fit together for later use. Thealigners and arch expanders may be directly fabricated as separatecomponents to be fit together later for use, for example. The archexpander comprises a force generating connector component as disclosedherein and the aligner comprises a teeth engagement structure asdisclosed herein. The separate components may comprises correspondingengagement structures that allow the components to fit together and holdthe aligner and connector component together when placed in the mouth ofthe patient. The corresponding engagement structures can be configuredin many ways and may comprise one or more of locking structures, aprotrusion sized to extend into a receiving structure such as a recess,nested structures or locking structures. The aligner and removableconnector component may comprise corresponding shape profiles that allowthe corresponding structures of the arch expander to aligner to fittogether and be held in place. In some instances, the correspondingstructures can be configured for the engagement structures to gentlyclick in place, for example. The user can be provided with a pluralityof pieces to use over the course of a treatment plan of arch expansion,for example.

A person of ordinary skill in the art will recognize that the forcegenerating connector components as shown in FIGS. 15A, 15B, 15C, 15D,and 16 can be sized for arch expansion in response appropriate forcesfor arch expansion and three dimensional shape profile data from a scanof an oral cavity of the mouth of the patient. The embodiments of FIGS.15A, 15B, 15C, 15D, and 16 are well suited for combination with theembodiments of FIGS. 1, 2, 3, and 4 , as well as FIGS. 11, 12, 13, 14A,and 14B—such as shown in FIG. 12 , for example. A person of ordinaryskill in the art will recognize that the connector components of FIGS.15A, 15B, 15C, 15D, and 16 can be sized in many ways, as may be desiredfor orthodontic use.

FIG. 15A illustrates a removable arch expander 1500 fabricated to matewith an orthodontic appliance. The arch expander 1500 comprises aconnector component 1501 fabricated from elastic material to fit thepalate of a patient. The material may be fabricated to be larger thanthe patient's arch region, so that it compresses when worn, permittingan outward force to be applied to a patient's teeth. The arch expander1500 further comprises a ridged portion 1502 on each side designed toconform to the surface of an orthodontic appliance. The rigid portion1502 may comprises protrusions sized and shaped to extend towardinterproximal the space of the teeth when engaging correspondingstructures of the teeth engaging appliance. In order to secure the forcegenerating connector portion of the arch expander to an orthodonticappliance such as an aligner, indentations 1503 may be located in theridged portion 1502 configured to mate with protrusions on theappliance.

FIG. 15B illustrates part of an aligner 1510 designed to mate with aconnector component as shown in FIG. 15A. The aligner 1510 comprises aplurality of teeth engagement structures comprising a plurality of teethreceiving cavities 1511 sized and shaped to engage the teeth for archexpansion. The aligner comprises plurality of tooth-receiving cavities1511, as well as a labial contour 1512. The labial contour 1512 matchesthe corresponding ridged portion 1502 of the connector component. Theteeth engaging aligner component further comprises protrusions 1513configured to engage, for example mate, with the correspondingindentations 1503 of the arch expander 1500. The protrusions 1513 can belocated on a labial side of the teeth. The teeth engaging alignercomponent may comprise receiving structures shaped to receive theprotrusions of the rigid portion 1502 of the connector component 1501.This arrangement allows the connector component 1501 and the aligner1510 to hold together, for example to securely mate together. Thealigner 1510 can be configured to move teeth in accordance with atreatment plan as described herein. The connector component 1501 can beconfigured to move the arch in accordance with an arch expansion plan.

The teeth engagement structures that couple to the teeth can beconfigured in many ways. Although an aligner is shown, other structuresas described herein can be used to engage the teeth and couple to theconnector component in order to engage the teeth.

FIG. 15C show a picture of a directly fabricated orthodontic appliance1520 comprising a palate expander that can be modified in accordancewith the present disclosure for arch expansion. The connector component1500 comprises mating structures as disclosed herein and is showncoupled to an aligner 1510. The connector component and aligner are madeof different materials, with the connector component capable of flexingwhen worn to store elastic energy, thereby applying force to a patient'steeth. The connector component comprises an unloaded free standingconfiguration with the engagement structures such as protrusion having aseparation distance on opposing sides of the connector component sizedlarger than corresponding structures of opposing sides of the arch ofthe aligner.

A 3D computer model 1530 of appliance 1520, which may for example begenerated when designing an orthodontic appliance according to methods200 or 300, is illustrated in FIG. 15D. A person of ordinary skill inthe art can use computer modeling and experimentation to determine theforces to the teeth appropriate for arch expansion, and determine thesize, shape and material of the connector component as described herein.The connector component can be sized to inhibit or avoid contact withthe arch in response to an oral scan to generate three dimensionalprofile data of the mouth as described herein.

FIG. 16 shows a design of an orthodontic appliance 1600 comprising aplastic aligner component 1601 and a metallic connector component 1602.The use of metal materials offers a number of advantages, such asgreater applicable force, lack of stress relaxation, durability,corrosion resistance, and easy sterilization. Biocompatibility is alsoreadily achieved, since the use of metallic material in orthodontics isalready used in the dental industry, and the selection of appropriatemetals will be apparent to one of ordinary skill in the art. Metallicaligners may be usefully fabricated using direct fabrication techniquessuch as Direct Metal Laser Sintering (DMLS), and in some cases may befabricated directly along with a directly fabricated plastic alignercomponent.

Direct Laser Sintering (DLS) of plastic material may also be used tofabricate one or more of the components as disclosed herein. Moreover,other direct fabrication techniques may be used in addition to, or as analternative to, laser sintering of plastic and/or metal. For example,stereolithography, selective laser sintering, fused deposition modeling,3D printing, continuous direct fabrication, and/or multi-material directfabrication may be employed for making part or all of the palate andarch expanders disclosed herein. Part or all of said palate and archexpanders may also be formed using indirect fabrication techniques, suchas thermoforming, for example. In some cases, a first part of anappliance can be formed using a first manufacturing process, andthereafter combined with a second part of an appliance formed using asecond manufacturing process. For arch or palate expanders comprisingthree or more parts, each part may be formed using a separate process,or some or all parts may be formed by the same process. A first part mayalso be fabricated by a first process, and thereafter a second part maybe formed around or upon the first part—for example, by 3D printing oneor more layers of material on a previously formed structure to generatea combined appliance comprising multiple parts and/or materials.

In some cases, it may also be desirable to incorporate electronic ormechanical components within an orthodontic appliance. Electronics maybe used, for example, to measure such quantities as force applied,movement of teeth, physical properties within the mouth, or complianceby the patient in wearing the appliance. Mechanical elements may be usedto vary force or movement of the appliance, for example, in response tomeasurements of force or movement by electronic sensors. To accommodatesuch electronics and mechanics, appliances may be fabricated withcavities into which appropriate devices may be inserted. In some cases,an appliance may be directly fabricated around an electronic ormechanical component, so that the component is contained within theappliance.

In many embodiments, it can be desirable to combine the arch expandersand palate expanders disclosed herein, to provide expansion of thepalate in combination with expansion of one or both arches or othermovement of the teeth. Expansion of the palate can cause movement of theteeth of the upper dental arch, which can change the shape of the upperarch as well as the alignment of the teeth of the upper and lowerarches. Consequently, it can be desirable to rearrange one or both ofthe upper and lower arches to compensate. In some cases, a sequence oforthodontic appliances comprising arch and palate expanders isfabricated to provide sequential expansions of a patient's palate andarch. For example, a patient's palate can be expanded by a palateexpander, and subsequently the lower arch can be expanded to align theupper and lower arches. In some cases, arch and palate expanders may beprovided for simultaneous use, such as expansion of the palate and upperarch by a palate expander in combination with an expansion of the lowerarch with an arch expander. A single appliance can also provide bothtooth moving forces—such as arch expansion forces or other orthodonticforces (such as rearrangements of specific teeth)—and palate expansionforces. For example, expansion of an arch or palate may change thespacing or orientations of teeth in an arch, which can be correctedeither simultaneously or subsequently with an appropriate orthodonticappliance, to close gaps or reorient teeth, for example. For example,palate expansion can cause the space between anterior teeth such asincisors to change, resulting in gaps or other tooth misalignments. Apalate expander as disclosed herein can further comprise teeth receivingcavities configured to apply forces to direct teeth of the patient intoa desired alignment as the palate expands. When designing the palateexpander, the movement of teeth and of the palate can be modeled and theteeth receiving cavities of the appliance can be designed to account forthe resultant expansion of the palate by applying forces to thepatient's teeth in order to bring them into proper orthodonticalignment. Such combined forces can obviate or reduce the need forfurther orthodontic correction after palatal expansion.

While preferred embodiments of the present disclosure have been shownand described herein, it will be obvious to those skilled in the artthat such embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. An apparatus to expand an arch of a patient, the apparatus comprising: a polymeric shell including: a plurality of teeth receiving structures configured to receive and resiliently reposition a plurality of teeth of the patient from an initial arrangement toward a target, wherein the plurality of teeth receiving structures comprise a first crosslinked polymer; and a plurality of retention portions including: a flexible retention portion, wherein the flexible retention portion comprises the first crosslinked polymer; and a stiff retention portion, wherein the stiff retention portion is configured to resist movement of a first of the plurality of teeth while allowing movement of a second plurality of teeth when the apparatus is worn, wherein both the flexible retention portion and the stiff retention portion are integral to the polymeric shell; and a force generating portion connected with cross-linking to the polymeric shell, wherein the force generating portion is shaped to span a space between opposing posterior teeth of the patient, wherein the force generating portion is configured to apply an expansion force on the arch to expand the arch toward a target distance between the posterior teeth, wherein the force generating portion is retained on the polymeric shell by the flexible retention portion, wherein the force generating portion comprises a second crosslinked polymer having a different crosslinking amount than the first crosslinked polymer, and wherein the first crosslinked polymer and the second crosslinked polymer are formed from a same prepolymer material.
 2. The apparatus of claim 1, wherein the force generating portion, the flexible retention portion, and the stiff retention portion have been directly fabricated together.
 3. The apparatus of claim 1, wherein the force generating portion comprises a stiff material.
 4. The apparatus of claim 1, wherein the force generating portion comprises one or more of a compressible material or a resilient compressible structure to generate force to the teeth when placed.
 5. The apparatus of claim 1, wherein the force generating portion comprises one or more of a compressible material, a hydratable material, or a resilient compressible structure to generate force to the teeth when worn.
 6. The apparatus of claim 1, wherein the plurality of teeth receiving structures comprises one or more of a plurality of teeth receiving cavities or a plurality of teeth receiving extensions shaped to extend at least partially around received teeth.
 7. The apparatus of claim 1, wherein the polymeric shell comprises lingual and buccal sidewalls, wherein the lingual sidewalls include a portion configured to form a ridge at an anterior portion of the arch, wherein the ridge forms a part of the stiff retention portion.
 8. The apparatus of claim 1, further comprising a gap extending in a mesial-distal direction and separating the polymeric shell into first and second adjacent portion, wherein the first adjacent portion comprises anterior teeth receiving cavities on a mesial side of the gap.
 9. The apparatus of claim 1, wherein the first crosslinked polymer comprises a styrenic block copolymer, a silicone rubber, an elastomeric alloy, a thermoplastic elastomer, a thermoplastic vulcanizate elastomer, a polyurethane elastomer, a block copolymer elastomer, a polyolefin blend elastomer, a thermoplastic co-polyester elastomer, or a thermoplastic polyamide elastomer.
 10. The apparatus of claim 1, wherein the second crosslinked polymer comprises a polyester, a co-polyester, a polycarbonate, a thermoplastic polyurethane, a polypropylene, a polyethylene, a polypropylene and polyethylene copolymer, an acrylic, a cyclic block copolymer, a polyetheretherketone, a polyamide, a polyethylene terephthalate, a polybutylene terephthalate, a polyetherimide, a polyethersulfone, or a polytrimethylene terephthalate.
 11. The apparatus of claim 1, wherein the force generating portion comprises sintered plastic.
 12. The apparatus of claim 1, wherein the second crosslinked polymer is stiffer than the first crosslinked polymer.
 13. An apparatus to expand an arch of a patient, the apparatus comprising: a polymeric shell including: a plurality of teeth receiving structures configured to receive and resiliently reposition a plurality of teeth of the patient from an initial arrangement toward a target, wherein the plurality of teeth receiving structures comprise a first crosslinked polymer; a plurality of retention portions including: a flexible retention portion integral to the polymeric shell; and a stiff retention portion integral to the polymeric shell, wherein the stiff retention portion is configured to resist movement of a first of the plurality of teeth while allowing movement of a second plurality of teeth when the apparatus is worn; and a force generating portion connected with cross-linking to the polymeric shell, wherein the force generating portion: is shaped to span a space between opposing posterior teeth of the patient; is configured to apply an expansion force on the arch to expand the arch toward a target distance between the posterior teeth; is retained on the polymeric shell by the flexible retention portion; and comprises a second crosslinked polymer having a different crosslinking amount than the first crosslinked polymer, wherein the first crosslinked polymer and the second crosslinked polymer are formed from a same prepolymer material; wherein the plurality of retention portions are crosslinked to the force generating portion.
 14. The apparatus of claim 13, wherein the second crosslinked polymer has less crosslinking than the first crosslinked polymer.
 15. The apparatus of claim 13, wherein the force generating portion, the flexible retention portion, and the stiff retention portion have been directly fabricated together.
 16. The apparatus of claim 13, wherein the second crosslinked polymer of the force generating portion is stiffer than the first crosslinked polymer of the plurality of teeth receiving structures.
 17. The apparatus of claim 13, wherein the force generating portion comprises one or more of a compressible material or a resilient compressible structure to generate force to the teeth when placed. 